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PSYCHOLOGICAL  REVIEW  PUBLICATIONS 


THE 


*  JUL  25  1911 
SEU)'! 


Psychological  Monographs 


EDITED  BY 

JAMES  R.  ANGELL,  University  of  Chicago 
HOWARD  C.  WARREN,  Princeton  University  {Index) 

JOHN  B.  WATSON,  Johns  Hopkins  University  {Review)  and 

ARTHUR  H.  PIERCE,  Smith  College  {Bulletin) 


Volume  XII 

1909-11 


PUBLISHED  BY 

THE  REVIEW  PUBLISHING  COMPANY 

41  NORTH  QUEEN  ST.,  LANCASTER,  PA. 

AND  BALTIMORE,  MD. 

Agents:  G.  E.  STECHERT  &  CO.,  London  (2  Star  Yard,  Carey  St.,  W.  C.); 
Leipzig  (Hospital  St.,  10);  Paris  (76  rue  de  Rennes) 


CONTENTS 


Three  Studies  from  the  Psychological  Laboratory  of  the 
University  of  Chicago: 

1.  A  Study  of  Sensory  Control  in  the  Rat.  Florence  Rich¬ 

ardson.  Pp.  124. 

2.  On  the  Influence  of  Complexity  and  Dissimilarity  on 

Memory.  Harvey  A.  Peterson.  Pp.  68. 

3.  Studies  in  Melody.  W.  Van  Dyke  Bingham.  Pp.  vi+88. 

4.  Report  of  the  Committee  of  the  American  Psychological 

Association  on  the  Teaching  of  Psychology.  Pp.  93. 

5.  Mental  Life  of  the  Rhesus  Monkey.  William  T.  Shep¬ 

herd.  Pp.  62. 

The  Monographs  in  this  volume  are  Nos.  48-52. 


1 


(♦  MAR  18  1910 

Psychological  Monographs 

Vol.  XII 
No.  I 


October,  1909 
Whole  No.  48 


THE 

Psychological 


Review 


HOWARD  C.  WARREN 
Pri>jcetom  University 


EDITED  BY 
J.  MARK  BALDWIN 


AND 


JOHN  B.  WATSON 
Johns  Hopkins  University 


JAMES  R.  ANGELL,  University  of  Chicago  {Editor  of  the  Psychological  Monographs) 


A  Study  of  Sensory  Control  in  the  Rat 


BY 


Fn  o  Vi  I  r  \  son. 

Florence  Richardson^^  Ph.D. 

Associate  Professor  of  Psychology,  Drake  University 


Studies  from  the  Psychological  Laboratory  of  the 

University  of  Chicago 


THE  REVIEW  PUBLISHING  COMPANY 

41  NORTH  QUEEN  ST.,  LANCASTER,  PA. 

AND  BALTIMORE,  MD. 


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I  desire  to  express  here  my  obligation  to  Professor  James 
R.  Angell  for  constant  assistance  and  encouragement.  I  am 
particularly  indebted  to  Professor  John  B.  Watson,  under 
whose  immediate  direction  the  experimental  work  here  pre¬ 
sented  was  undertaken  and  carried  out.  My  thanks  are  due 
also  to  Professor  Harvey  Carr  for  suggestions  and  criticisms 
of  the  manuscript,  and  to  Miss  Ethel  Chamberlain,  who  assisted 
me  during  a  portion  of  the  experimentation. 


CONTENTS. 


Introduction. 

a.  Problem  and  Scope  of  Present  Study .  I 

b.  General  Method .  3 

PART  FIRST. 

I.  Experimental  Results. 

A.  Tests  on  Problem  Box  i .  7 

1.  Description  of  Apparatus  and  of  the  Learning  Process .  7 

2.  Statement  of  Results: . .  10 

a.  On  Normal  White  Rats .  10 

b.  On  Normal  Black-and-White  Rats .  13 

c.  On  Blind  Rats .  15 

d.  On  Anosmic  Rats .  17 

3.  Summary  .  21 

B.  Tests  on  Problem  Box  II .  26 

1.  Description  of  Apparatus  and  of  the  Learning  Process .  26 

2.  Statement  of  Results: .  29 

a.  On  Normal  White  Rats .  29 

b.  On  Normal  Black-and-White  Rats .  32 

c.  On  Blind  Rats .  34 

d.  On  Anosmic  Rats .  34 

3.  Effect  on  Rats  of  Changing  Position  of  Plane  90°  to  Right .  38 

4.  Summary .  42 

C.  Tests  on  Problem  Box  III .  46 

1.  Description  of  Apparatus  and  of  the  Learning  Process .  46 

2.  Statement  of  Results: .  47 

a.  On  Normal  White  Rats .  47 

b.  On  Normal  Black-and-White  Rats .  49 

c.  On  Blind  Rats .  50 

d.  On  Anosmic  Rats .  52 

3.  Effect  on  Rats  of  Changing  Position  of  Box  and  Cage .  52 

4.  Summary .  58 

D.  Discussion  of  Curves  showing  Average  Time-records  of  Normal  and  of 

Defective  Rats  in  Learning  the  Maze .  60 

E.  General  Conclusions  Based  upon  Results  of  above  Tests .  61 

F.  Problem  IV .  69 

1.  Description  of  Apparatus  and  of  Method  of  Teaching  Rats  to 

Jump... . ^9 

2.  Jumping  in  Constant  Direction,  i.e.,  Apparatus  in  East -West  Posi¬ 

tion  .  76 


CONTENTS 


i.  Statement  of  Results .  7^ 

a.  On  Normal  White  Rats .  7^ 

b.  On  Normal  Black-and-White  Rats .  7^ 

c.  On  Blind  Rats .  79 

d.  On  Anosmic  Rat .  83 

ii.  Summary .  85 

3.  Effect  of  Changing  Direction  in  which  Jump  Must  be  Made .  85 

i.  Statement  of  Results .  88 

a.  On  Normal  White  Rats .  88 

b.  On  Normal  Black-and-White  Rats .  90 

c.  On  Anosmic  Rat .  92 

ii.  Summary .  92 

4.  Effect  of  Altering  Distances  between  Platforms .  93 

a.  Effect  of  Altering  Horizontal  Distance .  93 

I.  Statement  of  Results .  94 

a.  On  Normal  White  and  on  Normal  Black-and-White 

Rats .  94 

b.  Effect  of  Altering  both  Horizontal  and  Vertical  Distances .  .  95 

i.  Statement  of  Results .  96 

a.  On  Normal  White  and  on  Normal  Black-and-White 

Rats .  96 

ii.  Summary .  97 

5.  Conclusion .  98 


PART  SECOND. 


J.  f'ffect  of  Training  upon  the  Rats .  103 

I.  Experimental  Results .  103 

1.  Comparison  of  Records  of  Trained  and  of  Untrained  Rats .  103 

a.  Normal  White  Rats  on  Problem  1 .  103 

b.  Blind  Anosmic  Rat  on  Problem  1 .  106 

c.  Normal  White  Rats  on  Problem  HI .  107 

d.  Normal  Black-and-White  Rats  on  Problem  HI .  108 

e.  Blind  Rats  on  Problem  HI .  112 

2.  Summary  of  Facts .  114 

II.  Conclusions .  114 

B.  Individual  and  Sex  Differences  as  Shown  by  Behavior .  117 

1.  Sex  Differences .  117 

2.  Individual  Differences .  119 


PART  THIRD 


General  Conclusions 


123 


INTRODUCTION. 

a.  Problem  and  Scope  of  Present  Study. 

The  work  presented  here  grew  out  of  a  series  of  tests 
upon  the  rat,  begun  in  April,  1906.  Watson,*  in  an  investiga¬ 
tion  which  he  was  carrying  on  at  the  time,  had  found  that  the 
only  necessary  sensory  avenues  employed  by  the  rat,  in  learning 
the  maze,  were  the  kinaesthetic  and  organic,  and  that  visual, 
olfactory,  auditory  and  tactual  impressions  could  in  all  prob¬ 
ability  be  dispensed  with. 

The  present  problem  parallels  that  of  the  above  investigation 
and  may  be  briefly  stated  as  an  attempt  to  determine  the  func¬ 
tion  of  the  different  sense  organs  in  the  reactions  of  the  rat 
to  situations  requiring  various  types  of  movement.  In  prob¬ 
lems  like  that  of  the  maze,  the  general  activity  of  running  is 
the  one  most  utilized.  The  sensori-motor  arcs  need  only  to  be 
integrated :  Whereas  the  coordinations  which  are  employed  in 
the  learning  of  such  problems^  as  Nos.  I,  II,  and  III  of  the 
present  series  (such  as  digging,  bending  the  back  and  climb¬ 
ing  upward  through  holes;  stepping  on  a  plane  and  advancing 
upon  it  until  a  trap  door  falls;  raising  the  head  and  lifting  a 
latch  with  the  snout,  etc.)  are  not  so  habitual  to  the  animal. 
The  sensori-motor  arcs  involved  in  the  learning  of  these  prob¬ 
lems  must  be  established  more  or  less  de  riovo,  and  at  the  same 
time  be  combined  into  a  series  which  can  function  more  or  less 
automatically. 

It  may  be  assumed  that  since  running,  which  is  the  chief 
form  of  activity  involved  in  the  maze,  is  so  reflex-like  in  char¬ 
acter,  it  might  well  be  carried  out  by  the  use  of  kinaesthetic 
sensory  impressions  alone.  The  coordination  involved  in  prob¬ 
lems  of  the  manipulation  type,  not  being  so  reflex  in  character, 
would,  if  the  factors  involved  in  the  formation  of  human  habits 

‘  Watson,  J.  B.,  Psych.  Rev.,  Mon.  Supp.,  vol.  viii,  no.  2,  1907. 

*  These  problem  boxes  are  described  in  detail  further  on. 


2 


FLORENCE  RICHARDSON. 


may  by  analogy  be  assumed  to  hold  in  the  case  of  the  rat, 
require  the  cooperation,  at  first  {t.  e.,  at  least  during  the  learn¬ 
ing  process),  of  visual  and  olfactory  impulses,  provided  such 
were  at  hand.  Later  on  such  coordinations  might  in  their 
turn  be  controlled  by  kinaesthetic  means. 

The  general  type  of  coordination  in  the  maze,  is,  as  has 
been  stated,  that  of  running.  The  animal,  in  addition,  must 
learn  what  turns  to  make,  and  where  to  make  them.  Carr 
and  Watson’s  ^  later  report  of  work  with  a  maze  in  which  the 
length  of  the  alleys  may  be  changed,  goes  to  show  that  the 
knowledge  of  the  direction  of  the  turns  and  the  point  at  which 
they  occur,  is  governed  by  the  kinaesthetic  and  organic  char¬ 
acter  of  the  cues  for  the  turns.  This  fact  explains  the  success 
of  blind  and  anosmic  rats  in  learning  the  pathway  in  a  maze. 

In  Problem  I  of  the  present  series,  the  pathway  which  the 
animal  must  follow  is  more  complex  than  that  of  a  maze  in 
that  it  involves  climbing  down  from  the  top  of  a  box,  finding 
a  hidden  entrance  to  the  food  box,  digging  away  an  obstruc¬ 
tion,  crawling  under  a  board  and  up  through  an  opening. 
The  solution,  however,  is  more  simple  than  that  of  any  of  the 
others  in  that  it  demands  little  manipulation,  and  on  the  whole 
approaches  the  labyrinth  type  of  problem.  How  much  the 
guidance  from  vision  and  olfaction  may  assist  the  functionings 
of  kinaesthetic  and  organic  processes  in  the  learning  of  this 
type  of  problem  is  one  of  the  chief  questions  to  be  answered 
by  the  present  research. 

Problem  II  is  thought  to  be  still  more  difficult  for  the  rat. 
The  animal  must  learn  here  to  press  down  an  inclined  plane 
at  a  distance  from  the  box,  and  establish  the  association  of 
the  falling  of  the  plane  with  the  opening  of  the  door  of  the  food 
box.  It  is  possible  that  olfaction  might  render  the  food  stimu¬ 
lus  more  intense,  and  thereby  quicken  the  reactions  of  the 
animal;  but  the  question  we  are  more  concerned  with  is 
whether  the  olfactory  values  of  the  different  parts  of  the  envi¬ 
ronment,  such  as  the  smell  of  the  plane,  of  the  door  of  the 
food  box,  etc.,  aid  the  animal  in  adjusting  to  such  situations. 


'  Jour.  Comp.  Neur.  and  Psych.,  vol.  xviii,  no.  i,  1908,  p.  ayfF. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


3 


Vision  might  also  be  the  means  by  which  he  attains  his  orien¬ 
tation  in  such  an  open  space  as  surrounds  the  apparatus. 

In  Problem  III,  the  rat  must  raise  a  latch  holding  a  door 
in  place  in  order  to  reach  the  food.  The  area  in  which  the 
successful  movement  must  be  performed  is  very  circumscribed, 
being  only  the  immediate  locality  of  the  free  end  of  the  latch. 
Vision  may  be  necessary  to  locate  the  door  and  the  latch. 
Olfaction  may  possibly  play  a  considerable  role  here  likewise. 

Problem  IV  necessitates  the  rat’s  jumping  from  one  plat¬ 
form  to  another  in  order  to  obtain  food.  It  is  hardly  con¬ 
ceivable  that  this  coordination  could  be  successfully  executed 
■  for  any  considerable  distance  without  the  aid  of  vision. 

If  different  types  of  sensory  control  are  used  by  the  animal 
in  meeting  such  different  situations,  the  fact  should  become 
evident  in  a  comparison  of  the  behavior  of  normal  rats  with 
that  of  rats  deprived  of  the  use  of  the  important  sense  organs. 

In  carrying  out  this  investigation  groups  of  normal  white 
rats,  normal  black-and-white  rats,  blind  rats  and  anosmic 
rats^  were  used. 

During  the  course  of  the  above  research  the  experimenter 
collected  data  bearing  upon  the  questions  of  sex  and  individual 
differences,  and  on  the  possible  influence  of  previous  training. 
While  these  topics  were  subsidiary  to  the  main  problem,  the 
results  seem  of  sufficient  value  to  justify  their  presentation. 

b.  General  Method. 

The  experiments  which  are  here  reported  were  as  carefully 
controlled  as  possible:  the  tests  were  made  every  day  and  at  the 
same  hour  of  the  day.  Unless  otherwise  specified,  the  rats 
were  about  120  days  old  when  the  experimentation  began. 
This  standard  of  age  was  adhered  to  because  the  rats  at  this 
time  have  much  of  the  energy  of  youth  together  with  fully 
developed  neural  and  physiological  mechanisms.  Fidelity  to 
this  requirement,  as  may  be  imagined,  caused  the  experimenter 

‘  The  anosmic  rats,  with  one  exception,  died  during  the  ravages  of  an  infec¬ 
tion  which  afflicted  the  rat  laboratory.  The  group  had  only  partly  completed 
its  work.  On  this  account,  the  inter-comparison  of  the  records  of  normal  and 
of  defective  rats  is  not  as  complete  as  is  desired. 


4 


FLORENCE  RICHARDSON. 


much  difficulty.  A  need  for  a  group  often  arose  when  none 
in  the  laboratory  satisfied  the  demands.  This  frequently 
meant  a  considerable  delay  until  a  litter  of  the  proper  age  could 
be  found.  As  a  rule,  the  rats  had  been  bred  in  the  laboratory 
and  were  known  to  be  of  good  stock.  Males  and  females 
used  in  the  work  were  kept  in  separate  cages  and,  for  the  most 
part,  were  tested  on  separate  apparatus.  This  was  done  as 
a  check  to  any  possible  tendency  toward  tracking,  and  to 
minimize  the  emotional  disturbance  of  fear  caused  by  an 
unusual  odor.  The  problem  boxes  were  carefully  washed  and 
left  for  a  time  in  the  open  air  before  being  assigned  to  a  new 
group.  On  account  of  the  fact  that  the  rats  were  required  ‘ 
to  get  into  the  problem  box  for  food,  rather  than  to  release 
themselves  from  confinement,  it  was  necessary  to  inclose  the 
area  in  which  they  were  to  work.  A  larger  cage  of  wire  netting 
was  placed  over  the  problem  box,  which  is  spoken  of  in  later 
descriptions  as  the  control  cage.  When  an  animal  is  confined 
within  his  problem  box,  no  such  outer  cage  is  necessary.  But 
unless  a  rat  were — in  a  measure — confined,  his  insatiable  curi¬ 
osity  would  preclude  a  solution  of  his  problem  within  reason¬ 
able  time  limits. 

The  boxes  were  kept  covered  by  these  cages  when  not  in 
use  so  that  no  predatory  wild  rats  could  leave  an  odor  on  them. 
On  one  occasion  the  laboratory  boy  carelessly  removed  the 
control  cage,  and  left  a  problem  box  exposed.  Wild  rats  had 
evidently  been  about,  for  the  next  day  each  rat  introduced  into 
the  cage  became  exceedingly  timid  with  fright,  and  the  emo¬ 
tional  reaction  was  so  strong  and  so  persistent  that  it  necessi¬ 
tated  the  abandonment  of  the  series.  Upon  another  occasion, 
when  the  rats  which  had  just  finished  their  work  for  the  day 
were  eating  in  the  problem  box,  the  experimenter  killed  several 
wild  rats  which  had  been  caught  in  a  trap.  Every  effort  was 
made  to  remove  any  trace  of  odor  from  the  experimenter’s 
hands;  but  when  the  white  rats  were  carried  back  to  their 
living  cages  one  of  them  seemed  much  frightened.  The  next 
day  he  objected  to  being  handled  and  when  put  into  the  test 
cage  he  crouched.  When  he  moved  about  at  all,  he  slunk 
along  close  to  the  floor,  cringing,  and  became  quite  motionless 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


5 


at  any  loud  or  sharp  sound.  For  several  days  his  behavior 
suggested  fear,  and  only  after  the  fifth  day  had  passed  did  he 
revert  to  his  normal  behavior.  Possibly  it  is  not  necessary  to 
go  so  into  detail  in  these  matters.  But  those  who  have  worked 
with  animals  realize  how  difficult  it  is  to  maintain  constant 
conditions.  If  the  experimenter  takes  the  precaution  to  state 
explicitly  the  methods  of  control  in  the  work  reported,  it  inspires 
more  confidence  in  the  minds  of  those  who  wish  to  utilize  the 
results. 

Milk-soaked  bread,  except  where  otherwise  stated,  was  the 
food  stimulus  used.  Hunger  was  relied  upon  as  being  the 
most  constant  and  most  natural  incentive  to  activity.  The 
rats  were  allowed  to  eat  but  sparingly  of  the  food  after  the 
first  successful  efforts,  but  after  the  last  trial  for  the  day  had 
been  given  they  were  permitted  to  satisfy  their  hunger.  On 
the  whole  the  method  of  reward  was  adopted  as  the  most 
efficient  means  of  controlling  the  reactions  of  these  animals. 
The  rats  were  never  allowed  to  become  ravenously  hungry. 
Such  a  condition  puts  a  premium  upon  useless  and  frantic 
movements. 

The  food  in  the  problem  box  was  always  placed  in  the  same 
location.  The  position  of  the  food  box  in  relation  to  the  con¬ 
trol  cage,  and  of  both  to  the  points  of  the  compass,  was  con¬ 
stant.  The  rat  was  always  put  into  the  cage  at  the  same  point 
and  with  approximately  the  same  bodily  orientation.  As  the 
entrance  was  at  the  east  in  the  first  three  problems,  the  rat 
entered  the  control  cage  facing  west.  Particular  precaution 
was  taken  in  this  matter,  since  all  experiments  with  the  rat 
have  shown  him  to  be  very  susceptible  to  slight  changes  in  his 
environment.  He  has  a  tendency  to  establish  a  pathway  from 
the  entrance  to  the  food  box,  and  to  follow  it  carefully.  Unless 
he  attains  orientation  quickly  and  pursues  this  pathway  he 
becomes  confused.  This  confusion  is  evidenced  by  the  display 
of  the  same  random  activity  present  in  his  first  trial. 

Since  the  time  records  must  furnish  the  greater  part  of  the 
basis  of  comparison  in  these  problems  especial  care  was  taken 
to  maintain  constant  conditions.  Comparisons  were  to  be  made 
between  entire  groups,  and  between  individuals  of  the  same  or 


6 


FLORENCE  RICHARDSON. 


different  groups.  This  fact,  likewise,  necessitated  the  employ¬ 
ment  of  great  vigilance  in  experimentation. 

The  animals  were  always  tame  when  beginning  the  work 
and  were  accustomed  to  being  handled.  Every  group  was 
given  the  different  tests  in  the  same  serial  order.  On  account 
of  the  possible  influence  of  education,  groups  were  not  set  upon 
the  second  problem  without  the  experience  of  the  first.  While 
at  the  time  the  difference  between  the  work  of  trained  and  of 
untrained  rats  was  only  hypothetical,  the  results  reported  here 
(p.  103)  seem  to  justify  the  precaution. 

Care  in  maintaining  these  conditions — such  as  the  age  of 
the  rat;  amount  of  previous  training;  continuous  daily  experi¬ 
mentation;  and  an  equal  number  of  daily  trials — made  the 
work  difficult.  It  is  admitted  that  even  with  the  care  taken, 
the  conditions  were  not  ideal.  In  many  cases  a  comparison 
is  made  of  tables  and  curves  formulated  from  the  records  of 
groups  composed  of  unequal  numbers  of  individuals,  and  of 
unequal  sex  representation.  However,  the  writer,  at  least,  feels 
that  the  records  obtained  represent  very  fairly  the  abilities  of 
the  animals  experimented  upon.  While  much  in  the  way  of 
accidental  variation  is  doubtless  present,  the  records  on  the 
whole  are  reliable. 


PART  I 


I.  Experimental  Results. 

A.  TESTS  ON  PROBLEM  BOX  I. 

I.  Description  of  Apparatus  and  General  Statement  of  Learn¬ 
ing  Process. 

The  first  problem  box  used  was  a  modified  form  of  the  one 
used  by  SmalP  and  by  Watson.^ 

In  this  box  the  rat  has  to  dig  through  sawdust  in  order  to 
reach  the  entrance  of  the  food  box.  The  box  is  30  cm.  long, 
22.5  cm.  wide  and  17.5  cm.  high,  the  top  and  the  bottom  being 
of  inch  boards.  The  box  is  raised  by  supports  at  the  corners 
so  that  the  bottom  is  5  cm.  above  the  table  upon  which  the 
box  rests.  The  sides  and  ends  of  the  box  are  covered  with 
wire  netting.  The  netting  on  the  sides  extends  down  to  the 
table,  while  that  on  the  ends  goes  only  to  the  bottom  of  the 
box,  leaxing  an  open  alley  under  the  box  between  the  two 
extended  side  walls.  In  the  center  of  the  raised  floor  is  a 
rectangular  opening  through  which  the  rat  climbs  from  below 
into  the  box  to  obtain  food.  This  opening  is  8  cm.  by  10  cm. 
A  larger  opening  in  the  top  of  the  box,  10  cm.  by  12.5  cm., 
allows  the  experimenter  both  to  admit  the  food  and  to  remove 
the  animal  from  the  box  (see  fig.  I).  This  opening  has  a  thin 
board  cover  which  is  pivoted  on  a  screw  near  one  of  its  ends. 

During  experimentation  the  sides  and  ends  of  the  box  were 
covered  with  sawdust  to  the  height  of  the  floor  of  the  box. 
This  height  was  chosen  arbitrarily  to  insure  a  practically  con¬ 
stant  amount  of  sawdust  for  the  animal  to  remove.  A  wire 
netting  control  cage,  52.5  cm.  long,  37.5  cm.  high  and  37.5  cm. 
wide,  with  a  door  on  one  side,  was  placed  over  the  box. 

*  Am.  Jour.  Psych.,  vol.  xi.,  no.  2,  p.  135. 

^  Ammal  Education,  p.  14. 


8 


FLORENCE  RICHARDSON. 


The  problem  with  which  the  rat  is  confronted  is  the  necessity 
for  removing  the  sawdust  either  at  the  north  end  or  at  the 
south  end  of  the  box.  Since  the  east  and  west  sides  are  entirely 
covered  with  wire  netting,  movements  at  these  points  are  use¬ 
less.  The  rat  must  dig  away  a  quantity  of  sawdust,  crouch 
and  then  crawl  under  the  floor  of  the  food  box  proper,  and 
later  climb  up  through  the  hole  in  the  floor.  At  the  beginning 
of  the  test  the  animal  was  always  placed  on  the  top  of  the  box 
facing  west.  It  must  learn  to  descend  to  the  floor  of  the  cage, 
orient  itself  as  regards  the  north  or  south  end  of  the  box, 
and  dig  underneath  the  floor  of  the  food  box  as  described 
above.  As  has  been  stated,  the  pathway  which  the  animal 


Fig.  I. 


must  establish  is  relatively  simple,  and,  with  the  exception  of 
the  digging,  crouching  and  climbing  movements,  the  problem 
approaches  in  its  simplicity  that  of  the  labyrinth  type. 

The  above  task  was  presented  first  to  normal,  then  to  defec¬ 
tive  rats  in  the  hope  of  obtaining  evidence  for  the  type  of  sen¬ 
sory  control  utilized  by  the  rat  in  forming  such  an  association. 
The  normal  rats  furnished  the  standard  time  and  error  record 
with  which  the  records  of  the  defective  animals  were  compared. 

The  rats  at  work  upon  this  problem  were  fed  once  a  day 
for  three  days  in  the  box,  a  handful  of  sawdust  having  pre¬ 
viously  been  sprinkled  over  the  floor  to  accustom  them  to  its 
presence. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


9 


The  time  consumed  during  the  test  was  taken  by  means  of 
an  ordinary  stop-watch,  which  was  started  just  after  the  door 
of  the  cage  was  closed  after  admitting  the  animal,  and  was 
stopped  when  the  rat  had  all  four  feet  in  the  food  box. 

The  general  description  of  the  learning  processes  involved 
in  this  problem  may  be  easily  set  forth  by  a  reference  to  the 
following  notes  of  an  individual  taken  at  random  from  the 
records  of  the  normal  rats. 


Notes  on  the  Behavior  of  Normal  Female  Rat  IV  tn  learning  Problem  I. 


TRIAL. 

4/20/06 

I 

Examined  most  carefully  both  outer  cage  and  food  box. 
Seemed  to  get  odor  of  food  and  dug  two-thirds  length 
of  east  side.  Scratched  lightly  at  west:  active  but 
unfortunate.  Began  scratching  at  south,  but  gave 
up  immediately  and  began  at  east.  Dug  under  at 
west  end  of  north  side.  Did  not  enter  food  box  at 
once.  Time  17.65  min. 

2 

Entered  at  west  of  north,  with  few  useless  movements. 
Time  .25  min. 

3 

Entered  at  west  of  north.  Time  .15  min. 

4/21/06 

4 

Scratched  on  east  side,  left,  returned  again  to  east  and 
dug  frantically,  then  entered  from  south.  Time  i  .02 
min. 

5 

Scratched  at  east,  entered  at  south.  Time  .15  min. 

6 

Hesitated  for  an  instant  at  east,  but  did  not  scratch. 
Time  .08  min. 

4/22/06 

7 

Entered  without  useless  movements  from  the  south. 

• 

Time  .18  min. 

8 

Entered  at  north;  dug  spasmodically.  Time  .42  min. 

9 

South.  Time  .17  min. 

4/23/06 

10 

South.  Time  .12  min. 

II 

Went  to  south,  hesitated,  seemed  confused,  dashed  to 
north  and  in.  Time  .20  min. 

12 

North.  Time  .03  min. 

The  above  notes  show  many  characteristic  features  of  the 
learning  process.  The  quick  drop  from  high  to  low  time  record, 
which  may  be  seen  from  the  form  of  the  curve,  (Plate  I)  is  typical 
of  the  first  and  second  trials.  The  sudden  elimination  of 
useless  movements  is  not  always  so  pronounced  as  in  the  case 


10 


FLORENCE  RICHARDSON. 


noted  above.  Often  errors  persist  through  half  of  the 
series.  The  manner  of  the  elimination  of  errors  is  well  illus¬ 
trated  in  the  above  notes.  There  is  at  first  a  persevering  effort 
to  dig  through  at  the  east  or  west  side,  followed  by  less  and 
less  persistent  endeavor  at  these  places;  later  there  is  present 
only  a  hesitancy  in  passing  such  points,  and  finally,  as  the  habit 
progresses,  no  notice  of  them  at  all. 

This  procedure  quite  parallels  that  of  the  rat  in  eliminating 
his  errors  in  the  maze.  He  at  first  explores  the  cul-de-sac 
with  care,  then  runs  into  it  for  shorter  and  shorter  distances, 
hesitates  at  its  opening,  and  finally  disregards  it  utterly.  Such 
behavior  is  indicative  of  the  early  random  and  accidental 
nature  of  the  movements,  and  illustrates  one  phase  of  the  kin- 
aesthetic  character  of  control. 

2.  Statement  of  Results, 
a.  On  Normal  White  Rats. 

In  order  to  obtain  normal  records  with  which  to  compare 
the  records  of  defective  animals,  a  group  of  eight  white  rats 
was  used.  These  rats  were  I22  days  old,  all  of  one  litter 
and  were  healthy,  active  individuals.  Being  bred  in  the  labo¬ 
ratory  their  previous  ancestral  history  was  known  to  be  of 
the  best.  Four  of  them  were  males  and  four  were  females. 
None  had  been  used  previously  in  experimentation.  Table  I 
shows  the  average  records  of  this  group.  On  Plate  I  the 
graphic  representation  of  this  average  is  given. 

The  table  shows  also  the  maximum  and  the  minimum  time 
records  for  each  trial,  the  number  of  rats  whose  records  coin¬ 
cide  with  the  average  for  the  group  at  that  trial,  and  the  number 
whose  records  are  greater,  and  the  number  whose  records  are 
less  than  the  average.  Since  average  alone  is  not  always  an 
adequate  representation  of  the  accomplishments  of  a  group, 
these  few  supplementary  facts  are  added  to  make  the  average 
of  greater  value. 

When  the  records  were  tabulated,  the  rat  making  the  maximal 
and  the  animal  making  the  minimal  record  at  each  trial  was 
noted.  The  number  of  maximal  and  of  minimal  records  made 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


1 1 


Table  I. 

Showing  the  average,  the  minimum,  and  the  maximum  time-recordy  of  eight 
normal  white  rats  upon  Problem  I.  The  last  three  columns  show  the  number 
of  animals  whose  time  records  are  (/)  equal  to  the  average,  (2)  below  and  (j) 
above  the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM 

I. 

2. 

3- 

I 

min. 

7.04 

min, 

3-97 

min. 

17-65 

6 

2 

2 

1 .69 

.28 

7.20 

6 

2 

3 

.48 

•15 

•83 

4 

4 

4 

.80 

.20 

1.58 

3 

5 

5 

•35 

•13 

•75 

5 

3 

6 

•30 

•15 

1 .07 

7 

I 

7 

•25 

.  10 

•55 

5 

3 

8 

■23 

.  10 

•44 

5 

3 

9 

•27 

•15 

.68 

5 

3 

10 

.18 

.  12 

.50 

7 

I 

11 

.  16 

.07 

•30 

4 

4 

12 

•  13 

•13 

.28 

2 

6 

13 

•  15 

.07 

•42 

6 

2 

14 

.09 

.08 

.18 

5 

3 

15 

.  II 

.  10 

.22 

5 

3 

i6 

14 

.  10 

■35 

5 

3 

17 

.18 

.  1 1 

•48 

5 

3 

18 

•  13 

,10 

.20 

5 

3 

19 

.19 

.07 

•45 

5 

3 

20 

.09 

.  10 

•13 

4 

4 

21 

•  17 

.05 

.60 

7 

I 

22 

.  12 

.  10 

•33 

6 

2 

23 

.11 

.  10 

.20 

4 

4 

24 

•23 

.07 

•73 

7 

I 

25 

-14 

•05 

•  42 

6 

2 

26 

.  10 

.07 

.20 

5 

3 

27 

.08 

.05 

.18 

4 

4 

28 

.  12 

.05 

.22 

4 

4 

29 

•  15 

•05 

•45 

5 

3 

30 

.07 

•05 

•13 

I 

3 

4 

3' 

.07 

.06 

13 

5 

3 

32 

.06 

•05 

.09 

4 

4 

33 

.12 

.05 

•37 

6 

2 

34 

■  17 

.06 

•52 

5 

2 

35 

.09 

.04 

.18 

4 

4 

36 

.19 

.06 

1.03 

7 

t 

37 

•  14 

.07 

•50 

6 

2 

38 

.09 

.07 

.22 

5 

3 

12 


FLORENCE  RICHARDSON. 


Table  I. — Continued. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

39 

.09 

.07 

•13 

I 

4 

3 

40 

.09 

.07 

•45 

6 

2 

41 

.24 

.08 

1-33 

7 

I 

42 

•15 

.  06 

•33 

7 

I 

43 

.  12 

.06 

•23 

6 

2 

44 

.  II 

.04 

•33 

6 

2 

45 

.  10 

.07 

•32 

6 

2 

46 

.06 

•03 

.  12 

5 

3 

47 

.06 

•03 

.09 

6 

2 

48 

.06 

•03 

.  10 

4 

4 

49 

.06 

•03 

.  10 

4 

4 

50 

•23 

.08 

T  .26 

7 

I 

by  each  individual  was  then  given  its  percentage  value.  These 
percentages  are  shown  below. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 

MADE  BY  EACH  INDIVIDUAL. 

Ml  ntmal  Records.  Maximal  Records. 


per  cent. 


Male  1 .  41.6  Male  I. 

Male  II .  10.6  Male  II 

Male  III .  22.0  Male  III 

Male  IV .  10.6  Male  IV. 


Female  I .  i 

Female  II .  6 

Female  III .  3 

Female  IV .  5 


per  cent 
II 
8 
7 

24 


Female  1 .  29 

Female  II .  6 

Female  III .  7 

Female  IV .  8 


These  supplementary  tables  with  others  similar  in  character 
will  be  discussed  in  a  later  section  (p.  117).  They  are  inserted 
here  to  show,  in  a  measure,  how  dependent  the  average  may 
be  upon  the  variations  among  individuals.  Male  IV  and 
Female  I  are  responsible  for  more  than  one-half  of  the  longest 
r  cords.  Male  I,  on  the  other  hand,  though  he  has  not  the 
least  percentage  of  maximal  records,  has  made  more  than  two- 
fifths  of  the  total  number  of  minimal  records.  In  other  words, 


A  STVDT  OF  SENSORY  CONTROL  IN  THE  RAT.  1 3 

he  has  almost  as  many  minimal  records  per  trial  to  his  credit 
as  have  the  other  seven  combined. 

The  last  three  columns  of  Table  I  were  added  in  the  hope 
of  further  clarifying  the  table  and  the  curve.  These  columns 
show  roughly  to  what  extent  the  average  represents  the  group. 
Often  a  high  record  of  one  individual  will  raise  the  average  of 
the  group,  so  that  in  the  corresponding  curve  a  high  point  is 
a  result  of  the  long  time  record  of  one  rat.  The  rises  in  the 
curve  at  the  twenty-first,  thirty-fourth,  thirty-sixth,  forty-first 
and  fiftieth  trials  are  thus  explained  as  due  to  the  individual 
and  probably  accidental  variation  of  some  animal.  On  the 
other  hand,  on  the  sixth  and  tenth  trials  seven  rats  made  records 
below  the  average  without  skewing  the  curve. 

h.  On  Normal  Black-and-White  Rats. 

A  group  of  black-and-white  rats  was  set  to  work  on  the  series 
of  problems.  These  rats  were  females,  all  of  one  litter,  and 
were  112  days  old  when  experimentation  began.  They  had 
been  much  petted  from  infancy  and  were  unusually  tame. 

Table  II  shows  the  time-records  made  by  these  rats  and 
Plate  I  shows  the  graphical  representation  of  these  averages. 
This  group,  as  may  be  seen  by  a  glance  at  the  curve  solved 
the  problem  in  uniformly  less  time  than  the  normal  white 
rats,  not  only  with  the  time-records  much  lower  on  the  whole 
but  the  first  successes  were  accomplished  after  an  exceedingly 
short  interval. 

The  following  table  gives  the  percentage  of  minimal  and  of 
maximal  time-records  made  by  each  rat. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 

MADE  BY  EACH  INDIVIDUAL. 

Minimal.  Maximal. 


per  cent. 

per  cent. 

Female  I . 

.  51 

Female  I . 

.  16 

Female  II . 

.  13 

Female  II . 

.  18 

Female  III . 

.  27 

Female  III . 

.  25 

Female  IV . 

.  9 

Female  IV . 

.  41 

H 


FLORENCE  RICHARDSON. 


Table  II. 

Showing  the  average,  the  minimum,  and  the  maximumtime-records  of  four  black- 
and-white  females  upon  Problem  I.  The  last  three  columns  show  the  number 
of  animals  whose  time-records  are  (l)  equal  to  the  average,  (2)  below,  and 
(j)  above  the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

min. 

min. 

min. 

I 

.82 

•25 

1-53 

2 

2 

2 

•23 

.67 

•37 

2 

2 

3 

•23 

.67 

•52 

3 

I 

4 

.  12 

.07 

•  17 

2 

2 

5 

.76 

•05 

.11 

3 

I 

6 

•17 

.06 

•47 

3 

I 

7 

.08 

.07 

.12 

2 

2 

8 

.08 

.05 

.19 

3 

I 

9 

•13 

•05 

.22 

2 

2 

10 

.08 

.06 

.  10 

I 

3 

II 

.07 

.05 

.10 

3 

I 

12 

.06 

•05 

.06 

2 

2 

13 

.07 

•05 

.  10 

2 

2 

14 

.18 

.05 

•53 

3 

I 

15 

.06 

•05 

.09 

2 

2 

16 

.07 

•05 

.  10 

2 

2 

17 

.  10 

.07 

•14 

2 

2 

18 

.11 

.07 

.26 

3 

I 

19 

•05 

■05 

.06 

3 

I 

20 

.09 

.04 

•17 

2 

2 

21 

.05 

•03 

.07 

2 

2 

22 

.05 

.04 

.07 

2 

2 

23 

.04 

■03 

.05 

2 

2 

24 

.05 

•03 

.08 

2 

2 

25 

.05 

•03 

.06 

1 

2 

2 

26 

.06 

■03 

.  12 

2 

2 

27 

.  II 

■03 

•35 

3 

I 

28 

.04 

•03 

.04 

3 

I 

29 

.04 

■03 

.04 

I 

3 

30 

•03 

•03 

.04 

2 

2 

31 

.05 

•03 

.  10 

3 

I 

32 

.04 

.04 

.04 

I 

3 

33 

.04 

•03 

.04 

2 

2 

34 

.04 

•03 

.06 

3 

I 

35 

.04 

.04 

.05 

2 

2 

36 

•05 

■03 

.07 

2 

2 

37 

.06 

■03 

.  12 

3 

I 

38 

.07 

.04 

.09 

2 

2 

A  STUDT  OF  SENSORY  CONTROL  IN  THE  RAT. 


15 


Table  II. — Continued. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

39 

.04 

•03 

.05 

3 

I 

40 

.06 

.04 

.  12 

3 

I 

41 

•c>3 

.02 

.04 

2 

2 

42 

.06 

.04 

.  10 

2 

2 

43 

.08 

•03 

•17 

3 

I 

44 

.18 

.02 

•63 

3 

I 

45 

.06 

•05 

.07 

I 

3 

46 

.04 

•03 

•05 

2 

2 

47 

.04 

•03 

•05 

2 

2 

48 

.04 

.04 

.04 

2 

2 

49 

.04 

•03 

•05 

3 

I 

50 

•03 

•03 

.04 

I 

3 

c.  On  Blind  Rats. 

Nine  blind  rats  of  which  four  were  males,  and  five  were 
females,  were  trained  on  the  problem.^  The  animals  were 
about  four  months  old  and  all  were  in  excellentcondition. 

Table  III  gives  the  records  made  by  eight  animals  of  the 
group.  A  curve  on  Plate  I  shows  the  graphic  representation 
of  the  averages  given  in  this  Table. ^ 

Table  III. 

Showing  the  average,  the  minimum  and  the  maximum  time-records  of  eight 
blind  rats  upon  Problem  /.  The  last  three  columns  show  the  number  of 
animals  whose  records  are  (/)  equal  to  the  average,  (2)  below,  and  (5) 
above  the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3 

min. 

min. 

rniYi, 

I 

2-73 

.48 

6.41 

5 

3 

2 

•51 

•25 

1 .00 

5 

3 

3 

.91 

•23 

1.97 

4 

4 

4 

■73 

■17 

2.45 

6 

2 

5 

1.52 

I  .20 

8.06 

I 

6 

I 

6 

•  51 

.  10 

1.42 

5 

3 

‘  Cf.  Watson,  ibid,  pp.  47  ff. 

*  The  time-records  of  one  male  are  not  included  in  the  average.  They  are 
unusually  slow  and  are  discussed  in  the  paragraphs  on  individual  differences. 


i6 


FLORENCE  RICHARDSON. 


Table  III. — Continued. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMU 

7 

•23 

.  12 

.42 

8 

•49 

.07 

1-93 

9 

.70 

.04 

1 .92 

10 

.50 

•17 

1.63 

II 

.84 

.07 

3.60 

12 

•35 

.06 

•63 

13 

.28 

.07 

.67 

14 

•49 

•13 

I  13 

J5 

.28 

.05 

•53 

16 

.19 

•05 

.48 

17 

•17 

.04 

•42 

18 

1 .06 

•05 

6.13 

19 

•30 

•05 

•83 

20 

.21 

•05 

•52 

21 

•45 

•05 

1 . 10 

22 

.24 

.05 

•63 

23 

.42 

.04 

1.05 

24 

13 

.05 

•33 

25 

.  12 

•05 

•23 

26 

•37 

.07 

1 . 12 

27 

.18 

.09 

•32 

28 

•15 

•05 

•32 

29 

•57 

.07 

3-13 

30 

•31 

.07 

•45 

31 

•25 

.08 

•52 

32 

.18 

■05 

■42 

33 

•15 

.08 

•25 

34 

.27 

.07 

•75 

35 

•13 

.04 

•30 

36 

.  16 

•05 

•47 

37 

•23 

.07 

•78 

38 

.20 

.06 

.42 

39 

.26 

•37 

•87 

40 

.26 

.05 

.70 

41 

;  16 

•05 

•38 

42 

.26 

.04 

1 .02 

43 

•34 

•05 

1-33 

44 

.21 

.06 

•45 

45 

•25 

.07 

•92 

46 

.22 

•47 

•53 

47 

.18 

.06 

■49 

48 

.  21 

.07 

•42 

49 

•25 

.04 

•83 

50 

•^3 

i 

.04 

•45 

4 

6 

5 
4 

6 


.3 

2 

3 

4 
2 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT.  17 

The  averages  in  the  above  table  are  low,  but  lack  uniformity. 
There  was  wide  variation  among  the  individuals  of  the  group, 
which  was  noticeable  not  only  in  their  time  records,  but  in 
their  general  behavior. 

The  following  table  shows  the  number  of  minimal  and  of 
maximal  time-records  made  by  each  blind  rat. 


TABLE  SHOWING  PERCENTAGES  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS  MADE 

BY  EACH  INDIVIDUAL. 

Minimal.  Maximal. 


per  cent. 

% 

per  cent. 

Male  II . 

.  23 

Male  II . 

.  4 

Male  III . 

.  21 

Male  III . 

.  6 

Male  IV . 

.  6 

Male  IV . 

.  3 

Female  I . 

.  I 

Female  I . 

.  46 

Female  II . 

.  22 

Female  II . 

.  8 

Female  III . 

.  22 

Female  III . 

.  4 

Female  IV . 

.  2 

Female  IV . 

.  25 

Female  V . 

.  3 

Female  V . 

.  4 

Female  IV  made 

one-fourth. 

and  Female  I 

nearly  one-half 

of  the  total  number  of  maximal  records.  Males  II  and  III 
and  Females  II  and  III,  together  made  88  per  cent  of  the 
minimal  records. 


d.  On  Anosmic  Rats. 

Since  in  these  problems  the  animals  at  all  times  are  in  rela¬ 
tively  close  proximity  to  the  food  so  that  odor  stimuli  might 
affect  their  reactions,  five  anosmic  males  were  tested  upon 
the  problem.  Each  had  had  the  olfactory  bulbs  removed  as 
described  in  detail  by  Watson.^  The  animals  were  in  good 
condition  when  experimentation  was  begun — forty  days  after 
the  loss  of  the  bulbs — and  remained  so  throughout  the  test. 

Table  IV  gives  the  time-records.  The  graphical  representa¬ 
tion  made  from  the  average  is  shown  in  Plate  I. 

It  seems  unnecessary  to  comment  at  length  on  the  results 
given  in  the  table  and  curve.  The  effect  of  individual  varia- 


'  Ibid.  p.  49  fT. 


i8 


FLORENCE  RICHARDSON. 


Table  IV. 

Showing  the  average,  the  minimum  and  the  maximum  time-records  of  five  anos- 
mic  males  upon  Problem  I.  The  last  three  columns  show  the  number  of 
animals  whose  records  are  (/)  equal  to  the  average,  (2)  below,  and  (j)  above 
the  average. 


NO.  OF 

TRIAL. 

AVERAGE 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

I 

mtn. 

13.27 

min. 

1 .62 

min. 

46.30 

4 

I 

2 

•63 

•25 

1 .98 

4 

I 

3 

.22 

•13 

.40 

3 

2 

4 

•32 

•  14 

•52 

3 

2 

5 

.28 

.07 

.62 

3 

2 

6 

•43 

.07 

2.92 

4 

I 

7 

.26 

.07 

•50 

2 

2 

I 

8 

•57 

.  10 

2.22 

4 

I 

9 

•32 

.07 

•73 

3 

2 

10 

.14 

.07 

•23 

3 

2 

II 

.20 

.07 

•43 

3 

2 

12 

■31 

.07 

.98 

4 

I 

^3 

•30 

.07 

.90 

4 

I 

H 

.20 

.06 

•37 

3 

2 

15 

31 

.06 

.67 

2 

3 

16 

•36 

•  13 

•63 

3 

2 

17 

.22 

.06 

.40 

2 

3 

18 

.28 

.  16 

•50 

3 

2 

19 

.20 

.07 

•43 

3 

2 

20 

•24 

.08 

•47 

3 

2 

21 

.  16 

•03 

■25 

3 

2 

22 

■32 

.05 

.78 

2 

3 

23 

•35 

.07 

1-05 

4 

I 

24 

.21 

.05 

•42 

3 

2 

25 

•14 

.08 

.22 

3 

2 

26 

•23 

.06 

•  42 

2 

3 

27 

.20 

.07 

•37 

2 

3 

28 

•30 

.07 

.67 

2 

3 

29 

•27 

.06 

.62 

2 

3 

30 

.  16 

•  13 

•24 

3 

2 

31 

.20 

.07 

•  42 

2 

3 

32 

•27 

.05 

.48 

2 

3 

33 

•29 

•05 

.82 

4 

I 

34 

•17 

.06 

■33 

4 

I 

35 

.28 

.07 

.70 

3 

2 

36 

•57 

.04 

1 .60 

3 

2 

37 

•39 

•05 

1. 18 

3 

2 

38 

•17 

.04 

•32 

3 

2 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


19 


Table  IV. — Continued. 


NO.  OF 

TRIAL 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3* 

39 

•32 

.08 

•63 

3 

2 

40 

.28 

.08 

•53 

3 

2 

41 

.27 

.07 

•38 

2 

3 

42 

.29 

.06 

•55 

3 

2 

43 

.28 

•13 

•42 

I 

2 

2 

44 

.40 

.28 

.67 

3 

2 

45 

.22 

.08 

•38 

3 

2 

46 

•35 

.08 

•75 

3 

2 

47 

•25 

•05 

.68 

3 

2 

48 

.29 

•05 

•93 

4 

I 

49 

.24 

.09 

•43 

2 

2 

«;o 

•  41 

.07 

1-13 

4 

I 

tions  on  the  curve  is  roughly  shown  in  the  table  below,  which 
gives  the  percentage  of  minimal  and  of  maximal  records  made 
by  each  rat. 


TABLE  SHOWING  PERCENTAGES  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS  MADE 

BY  EACH  INDIVIDUAL  RAT. 

Minimal.  Maximal. 


per  cent. 

per  cent. 

Male 

P . 

.  0 

Male 

T . 

.  55 

Male 

H . 

.  6 

Male 

H . 

.  10 

Male 

HI . 

.  38 

Male: 

HI . 

.  6 

Male 

TV . . 

.  56 

Male 

IV . 

.  2 

Male 

V . 

.  0 

Male 

V . 

.  27 

Male  I,  as  is  indicated,  made  more  than  one-half  of  the  longest 
time-records:  the  time-records  of  Male  V  were  also  long. 
Were  it  not  for  the  eccentricities  of  these  two  rats,  the  curve 


^  The  emotional  attitude  of  Male  I,  together  with  a  tendency  to  gnaw  at  all 
that  came  in  his  way  was  responsible  for  his  apparent  slowness.  He  was  a  very 
active  and  hardy  rat,  but  his  efforts  were  entirely  misdirected.  He  spent  much 
of  his  time  endeavoring  to  clamber  from  the  top  of  the  box,  and  once  down,  was 
more  than  likely  to  climb  back  up  immediately  and  begin  all  over  again  his  frantic 
attempts  to  get  off.  When  he  did  spend  any  length  of  time  on  the  floor  of  the 
cage,  he  vented  his  energy  in  'gnawing  at  the  outer  cage,  or  at  the  wire  netting 
of  the  food  box.  On  later  problems  his  propensity  to  gnaw  became  the  despair 
of  the  experimenter,  as  it  necessitated  perpetual  repairing  of  the  apparatus.  Rat 
V  likewise  spent  much  time  in  the  endeavor  to  get  off  the  box.  He  finally 
acquired  the  habit  of  getting  off  at  a  point  nearest  the  door.  Later,  if  he  did 
not  at  once  reach  this  position,  he  seemed  utterly  at  a  loss  what  to  do. 


rimittfcS 


20 


FLORENCE  RICHARDSON. 


•i 

d 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


21 


for  this  group  would  have  been  considerably  lower  than  it  is. 
The  records  of  Male  IV  were  exceptionally  short. 

J.  Summary. 

a.  Average  Time-records  for  the  Total  Series  of  Fifty  Trials. 

In  attempting  to  summarize  the  results  of  tests  with  different 
groups  of  rats  upon  this  problem,  only  a  comparison  of  the 
records  made  by  the  normal  and  the  defective  animals  will  be 
given  here.  The  discussion  of  the  records  and  a  theoretical 
interpretation  of  them  together  with  the  facts  brought  out  in 
later  summaries  will  be  given  in  the  final  conclusions  at  the 
end  of  Part  I  (p.  6i). 

The  sum  of  the  separate  time-records  for  the  entire  series 
of  fifty  trials  given  each  rat  was  obtained,  and  it  was  then 
divided  by  the  total  number  of  trials  given  that  animal.  This 
gave  an  average  time-record  for  each  animal  on  the  problem 
and  afforded  one  basis  for  the  comparison  of  records  of  indi¬ 
viduals.  From  the  individual  averages  obtained  as  above 
described  a  group  average  was  made  which  serves  as  an  addi¬ 
tional  means  of  comparing  the  records  of  groups  of  normal 
rats  with  those  of  the  groups  of  defective  animals. 

TABLE  SHOWING  GROUP  AVERAGE  OF  THE  TOTAL  TIME  (50  TRIALs)  CONSUMED 
BY  NORMAL  AND  BY  DEFECTIVE  RATS  IN  LEARNING  PROBLEM. 

Average  Records  of  Groups. 


Black-and-White.  . 
White . 

A verag 

mtn, 

. 09  Blind  . 

es  of  Records  of  Individuals  in 

the  Groups. 

mtn. 

•49 

•55 

BLACK-AND- 

-WHITE. 

WHITE. 

BLIND. 

ANOSMIC. 

min. 

min. 

mtn. 

mtn. 

Female  I 

.  10 

Male  I  .36 

Female  I 

.11 

Male 

I 

.65 

Female  II 

.08 

Male  II  .39 

Female  II 

.42 

Male 

II 

•25 

Female  III 

.09 

Male  III  .38 

Female  III 

.24 

Male 

III 

I  .09 

Female  IV 

.08 

Male  IV  .27 

FemalelV 

•47 

Male 

IV 

•17 

Female  V 

•32 

Male 

V 

.60 

Female  I  .41 

Male  I 

•97 

Female  II  .20 

Male  II 

•31 

Female  III  .27 

Male  III 

•27 

Female  IV  .46 

Male  IV 

•27 

22 


FLORENCE  RICHARDSON. 


As  may  be  noted  in  the  above  table  the  average  of  the  group 
of  black-and-white  rats  is  phenomenally  low  as  compared  with 
that  of  the  other  groups.  The  individual  averages  of  this 
group  are  very  uniform.  The  highest  individual  average, 
which  is  .10  min.,  is  just  one-half  of  the  lowest  average  made 
by  any  one  normal  white  rat,  viz.,  .20  min.  The  group  aver¬ 
age  of  the  blind  rats  is  high,  but  the  high  variations 
among  individuals  are  in  part  responsible  for  the  high  group 
average.  Five  individual  averages  among  the  blind  are  lower 
than  the  group  average  of  the  normal  white  rats,  and  the  lowest 
average  of  a  blind  rat,  .24  min.,  is  but  little  above  that  of 
the  lowest  individual  of  the  normal  white  rats,  .20 min.  The 
average  of  the  anosmic  group  is  very  slightly  lower  than  that  of 
the  blind  group,  though  here,  too,  the  individual  variation  is  high. 
The  average  made  by  Male  II  of  this  group  is  the  lowest  made 
by  any  normal  or  defective  white  rat  upon  the  problem. 

b.  Average  Time  Records  by  Groups  of  Ten  Trials. 

The  time-records  of  each  individual  were  averaged  by  tens. 
The  interesting  fact  was  brought  out,  that  of  the  total  of  twenty- 
six  normal  and  defective  animals,  seventeen  made  lower 
averages  on  the  second,  third  or  fourth  ten  than  upon  the  fifth. 
In  other  words:  almost  two-thirds  of  the  total  number  of  rats 
reached  their  period  of  highest  speed  early  in  the  series  of 
fifty  trials,  and  later  lengthened  their  time-records. 

The  average  time-records  b)  tens  of  the  individual  animals 
are  given  below.  The  starred  averages  show  those  instances 
in  which  the  average  time-record  of  a  series  of  tens  is  shortest 
before  the  last  ten  of  the  entire  series. 


TABLE  SHOWING  AVERAGES  OF  TIME-RECORDS  BY  GROUPS  OF  TEN. 

Black-and-whtte-Rats. 

Individuals. 


TRIALS 

FEMALE  I 

FEMALE  II 

FEMALE  III 

FEMALE  IV 

GROUP 

min. 

mtn. 

min. 

min. 

min. 

I-IO 

•  15 

.20 

.26 

.21 

.21 

I  1-20 

•  13 

.06 

.07 

.07 

.08 

21-30 

.06 

.04* 

.07 

.04 

.05 

31-40 

.05* 

•05 

•03* 

.03* 

.04* 

41-50 

.  1 1 

.06 

.04 

.04 

.06 

A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


^3 


Normal  White  Rats. 


MALE  I 

MALE  II 

MALE  III 

MALE  IV 

AV.  MALES 

GROUP 

mill. 

min. 

mm. 

mtn. 

min. 

min. 

I-IO 

1-45 

1.36 

1 .08 

■70 

1. 15 

I  .  16 

11-20 

•13 

.  16 

.11* 

.22 

•15 

•H 

21-30 

•09 

.  12 

•14 

.19 

.13* 

12* 

31-40 

•09 

.  10* 

•37 

.  12* 

•17 

•15 

41-50 

.06 

.21 

.21 

■  13 

■15 

■14 

FEMALE  I 

FEMALE  II 

FEMALE  III 

FEMALE  IV 

AV.  FEMALES 

min. 

mtn. 

min. 

min. 

min. 

min. 

I-IO 

1 .08 

.66 

.98 

2.02 

1. 18 

11-20 

.  14* 

•  15 

.  12 

.07 

.  II 

21-30 

.19 

.07 

.  16 

'  -04 

.11 

31-40 

.29 

.06 

.06 

.  II 

13 

41-50 

■35 

.06 

.05 

.04 

.  12 

Blind  Rats. 


^  MALE  I 

MALE  11 

MALE  III 

MALE  IV 

AV.  MALES 

GROUP 

mtn. 

mtn. 

min. 

mtn. 

min. 

min. 

I-IO 

1. 51 

•83 

•65 

•58 

•89 

■94 

1 1-20 

•33* 

.26 

.21 

•  17 

.24* 

•41 

21-30 

.80 

.28 

.21 

.21 

•37 

•35 

31-40 

1.25 

.  1 1 

.09* 

•24 

■42 

•43 

41-50 

.98 

.  10 

.  16 

■  15 

•35 

•31 

FEMALE  I 

FEMALE  II 

FEMALE  III 

FEMALE  IV 

FEMALE  V 

AV.  FEMALE 

min. 

min. 

min. 

min. 

mtn. 

mtn. 

I-IO 

I -  .33 

1-50 

■45 

.66 

•73 

■97 

1 1-20 

1-38 

1. 17 

.20 

.68 

.26 

•54 

21-30 

.81 

.19 

.24 

.30* 

.16* 

•34* 

31-40 

1 .21 

•14 

.21 

•38 

.21 

•43 

41-50 

.62 

.09 

.09 

•33 

.24 

•27 

Anosmic  Rats. 


MALE  I 

MALE  II 

MALE  III 

MALE  IV 

MALE  V 

GROUP 

mm. 

min. 

mm. 

min. 

min. 

mm. 

min. 

I-IO 

1 .21 

•30 

5.00 

•41 

I -43 

1 .67 

11-20 

.39* 

.22 

•  14 

■  15 

.46 

•27 

21-30 

•42 

■29 

.  10 

.08* 

.28* 

•23* 

31-40 

.60 

.20* 

.06* 

.09 

•.50 

•29 

41-50 

.61 

•25 

■  14 

.  1 1 

■32 

.28 

24 


FLORENCE  RICHARDSON. 


The  occurrence  of  the  minimum  time-records  early  in  the 
series  may  have  been  due  to  some  accidental  condition,  such 
as  a  variation  in  the  state  of  hunger.  However,  the  beha¬ 
vior  of  the  animals  as  well  as  their  time-records  often  indi¬ 
cated  a  falling  apart  of  the  stages  of  the  association,  suggesting 
rather  a  process  of  dissociation,  or  dissolution  of  the  association. 
This  might  be  the  effect  of  a  possible  decrease  in  the  intensity 
of  the  stimulus  as  the  reaction  became  automatic.  The  matter 
is  commented  upon  here  as  seeming  to  be  a  situation  in  which 
an  habitual  coordination  tends  to  break  down  through  a  rela¬ 
tively  long  continuance.  In  order  to  ascertain  whether  the  rats 
again  would  lower  their  records  for  later  periods  of  ten  trials, 
or  whether  the  coordination  really  disintegrated,  the  series 
should  have  been  continued  indefinitely,  and  possibly  should 
have  been  controlled  by  changing  the  kind  of  food  used  as  a 
stimulus.  Lack  of  time  prevented  the  continuation  of  this 
problem. 

c.  Discussion  of  Errors  in  this  Problem. 

The  computation  of  errors  which  were  made  by  the  animals 
has  been  computed  not  upon  the  basis  of  the  total  number 
of  useless  movements,  but  upon  that  of  particular  kinds  of 
random  movements,  namely,  those  by  means  of  which  a  rat 
attempts  to  enter  the  food  box  from  the  east  or  west,  whereas, 
he  can  only  enter  from  the  north  or  south.  In  tabulating 
the  results,  then,  the  attempts  to  dig  away  the  sawdust  at  the 
east  or  west  is  counted  an  error. 

The  number  of  errors  is  not  alone  an  accurate  standard  in 
the  learning  process  of  this  problem.  Often  an  error  crops 
out  in  a  trial  late  in  the  series  after  the  rat  has  made  many 
perfect  trials.  As  an  instance  of  this  may  be  cited  particularly 
the  case  of  one  rat,  black-and-white  Female  IV,  which  made 
four  errors,  one  each  at  her  fourth  trial,  twelfth,  thirty-fifth 
and  thirty-eighth  trial.  At  the  thirty-fifth  trial  her  time  was 
somewhat  longer,  though  at  the  thirty-eighth,  with  an  error 
at  another  position,  it  was  at  her  reaction  time:  .05  min.  The 
scratching  in  these  last  two  trials  might  have  been  a  move¬ 
ment  which  was  a  reversion  to  her  two  early  errors,  or  to  an 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


25 


accidental  movement  set  off  by  contact  with  the  sawdust  at 
that  point. 

Rat  IV  of  the  anosmic  group  made  but  one  error  and  that 
at  the  first  trial.  Two  black-and-white  females  made  each  one 
error,  at  the  sixth  and  ninth  trials  respectively. 

The  average  number  of  errors  for  the  different  groups  is  here 
given. 

Average  Total  Number  of  Errors. 

Normal  White .  8.2  Blind .  lO. 

Black-and-white .  2.7  Anosmic .  5.2 

Average  Number  of  Trials  Characterized  by  Errors. 

Normal  White .  7.2  Blind .  9.7 

Black-and-white .  2.5  Anosmic....  4.4 

d.  Comparison  of  the  Curves  of  the  Different  Groups. 

Plate  I  shows  the  curves  plotted  from  the  average  time- 
records  of  the  different  groups.  The  curve  representing  the 
group  of  black-and-white  rats  is  the  lowest  curve  of  the  four. 
Even  at  the  first  trial,  it  does  not  rise  above  the  coordinate 
representing  one  minute,  and  for  most  of  the  time  it  runs  below 
that  representing  .1  min.  The  curve  is  not  only  low,  but  is 
remarkably  uniform.  Whether  or  not  the  lowness  and  uni¬ 
formity  is  due  to  the  fact  that  these  rats  possess  pigmented 
eyes  will  be  discussed  in  the  conclusions  (p.  61). 

The  curve  representing  the  averages  of  the  normal  white 
rats  approximates  more  nearly  than  any  other  the  character 
of  the  curve  representing  the  black-and-white  rats.  At  the 
first  trial  this  curve  is  much  higher,  and,  until  the  fourteenth 
trial,  does  not  reach  so  low  a  point  as  the  curve  of  the  black-and- 
white  animals.  Again  at  the  twentieth,  the  twenty-seventh 
and  the  forty-fourth  trials  the  curve  goes  below:  otherwise,  it 
is  higher  and  more  variable. 

The  curves  representing  the  averages  of  the  blind  and  the 
anosmic  rats,  respectively,  are  much  alike  and  are  slightly 
higher  than  those  of  the  normal  rats.  Both  curves  are  irregular, 
and  both  follow,  in  general,  about  the  same  level.  The  curve 
of  the  anosmic  group  is  considerably  lower  at  the  third,  fourth 
and  fifth  trials,  than  that  of  any  other  group  of  albino  rats. 


26 


FLORENCE  RICHARDSON. 


From  the  sixth  trial  these  curves  cross  and  re-cross  each  other 
continually. 

B.  TESTS  UPON  PROBLEM  BOX  II. 

I.  Description  of  Apparatus  and  of  the  Learning  Process. 

The  apparatus  used  in  the  second  test  of  the  series  consists 
of  a  box,  20  cm.  by  20  cm.  at  the  base  and  15  cm.  high,  of 
wire  netting  of  a  centimeter  mesh.  A  door,  7  cm.  high  by 
10  cm.  long,  is  hinged  at  the  lower  corner  of  one  side  of  the 
box  (see  figure  2).  A  latch,  on  the  inside  is  controlled  by 
a  cord  passing  from  the  latch  upward  through  a  mesh  above, 
back  over  a  small  wooden  pulley  to  the  inclined  board  plane. 


Fig.  2. 


22  cm.  long  by  10  cm.  wide,  the  foot  of  which  rests  at  a  dis¬ 
tance  of  1 1  cm.  from  the  side  of  the  box  opposite  the  door. 
The  angle  which  the  plane  made  with  the  floor  of  the  experi¬ 
mental  cage  was  approximately  15°.  This  angle  was  decreased 
slightly  when  smaller  animals  were  used. 

When  the  rat  steps  upon  the  plane,  the  plane  falls,  and  the 
latch  is  thereby  pulled  up  allowing  the  door  to  fall  inwards  of 
its  own  weight.  In  this  test  there  is  required  a  series  of  adjust¬ 
ments  on  the  part  of  the  rat  which  is  quite  different  from  that 
demanded  of  him  in  Problem  I.  The  question  to  answer  is, 
as  was  the  case  in  the  learning  of  the  problem  just  discussed: 
Does  the  animal  use  olfactory  and  visual  impulses  in  the  forma¬ 
tion  of  these  new  and  unusual  coordinations,  and  if  so  to 
what  extent 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


27 


The  method  of  procedure  in  this  test  followed  closely  that 
just  reported.  The  box  was  enclosed  in  a  large  wire  control 
cage  72  cm.  by  76  cm.  and  37  cm.  high,  which  could  be  raised 
when  desired  so  as  to  admit  the  rat.  The  position  of  the  box 
remained  constant,  being  determined  by  means  of  several 
tacks  in  the  table,  which  prevented  the  box  from  slipping. 
The  plane  was  also  kept  in  position  by  tacks  at  the  margin 
nearest  the  box. 

The  animals  which  were  used  in  Problem  I  were  used  in 
the  present  test.  All  the  animals  thus  had  had  previous  experi¬ 
ence  in  experimentation,  and  this  previous  experience  was  of 
the  same  amount  and  kind.  The  results  of  other  tests  (see 
p.  103)  show  this  point  to  be  one  of  importance  in  the  control 
of  experimentation  with  rats.  Three  trials  per  day  for  ten 
days,  and  hve  trials  per  day  for  four  days  were  given,  making 
as  before  fifty  trials  in  the  series. 

The  solution  of  this  problem  is  unique  in  that  it  necessitates 
the  reaction  of  the  rat  at  a  distance  from  the  food  box.  On 
this  account,  the  learning  curve  from  the  second  to  about 
the  tenth  trial  is  much  more  irregular  than  that  of  Problem  I. 
(See  Plate  II.)  There  is  likely  to  be  a  second  pronounced  rise 
in  the  curve  after  the  first  trials.  This  is  explained  by  the 
fact  that  after  the  first  two  or  three  accidental  successes,  the 
rat  comes  to  associate  the  position  of  the  door  with  the  food,  but 
not  the  position  of  the  plane  with  the  food.  Consequenth',  the 
animal  goes  directly  to  the  door,  and  finding  it  closed,  begins 
to  scratch  and  gnaw  at  it  vigorously.  This  is  an  almost 
invariable  procedure.  The  time  so  spent  is  the  cause  of  the 
rise  in  the  curve. ^ 


*  The  experimenter  found  it  necessary  to  secure  the  latch  firmly  during  the 
time  the  rat  spent  tugging  at  the  door,  for  when  the  pressure  of  the  door  was 
released  from  the  latch,  the  weight  of  the  plane  raised  the  latch  and  allowed  the 
rat  to  reach  its  food  without  performing  the  desired  reaction.  At  first  a  hemp 
cord  was  run  through  a  hole  in  the  table  under  the  box  and  attached  to  the  latch. 
In  this  way  the  latch  could  be  held  firmly  by  the  experimenter  when  necessary, 
and  loosened  at  once.  Later  when  needed  a  long  wire  slipped  between  the 
meshes  of  the  cage  and  box  and  manipulated  by  the  experimenter  performed  the 
same  duty  more  surely  and  more  easily. 


28 


FLORENCE  RICHARDSON. 


An  account  of  the  procedure  of  one  individual  is  given  here 
as  indicative  of  the  learning  process. 


Diary  Record  of  Black-and- White  Female  I  on  Problem  Box  II. 


TRIAL. 

6/5/07 

I 

Went  at  once  to  door  of  box,  ran  around  box  rapidly 
stopping  only  to  sniff  at  food;  struck  the  plane  once, 
but  too  lightly.  Gnawed  industriously  at  door  then 
ran  about  cage.  Door  fell  at  2.33  min.  without 
attracting  her  attention;  she  found  opening  at  3.07 
min.  and  entered.  Time:  3.07. 

2 

Worked  at  door  fiercely  and  persistently,  occasionally 
dashed  around  box.  Door  fell  at  2.00  min.,  in  at 
2.12  min. 

3 

To  door  first,  then  round  and  round  box  several  times. 
Plane  fell  at  1.50  min.,  in  at  1.55  min. 

6/6/07 

4 

Very  active,  but  confined  activity  too  near  to  box.  In 
at  once  after  door  fell.  Time:  1.78  min. 

5 

Stayed  too  close  to  box.  Time:  1.78  min. 

6 

Had  bad  luck;  was  almost  too  active;  jumped  over  plane 
or  went  around  it.  Door  fell  at  8.53  min.  The  rat 
got  up  on  food  box  and  spent  much  time  in  sniffing 
the  air.  Entered  at  11.80  min. 

6/7/07 

7 

Door  fell  at  .67  min.,  in  at  .72  min. 

8 

Door  fell  at  .80  min.,  in  at  .88  min. 

9 

See  sixth  trial.  Time:  1.38  min.,  in  at  1.50  min. 

6/8/07 

10 

Door  fell  at  .07  min.,  in  at  .10  min. 

II 

Door  fell  at  .03  min.,  in  at  .06  min. 

12 

Rat  went  directly  to  door,  then  to  plane,  then  back  to 
door  at  once.  Door  fell  at  .13  min.,  in  at  .17  min. 

6/1 1/07 

18 

Went  as  usual  directly  to  plane  and  over  it,  but  too 
near  base,  consequently  door  did  not  fall;  rat  then 
went  to  door,  came  back  to  plane  at  once,  over  and 
to  the  then  open  door.  The  association  seems 
firmly  fixed.  Time:  18  min. 

The  record  of  this  black-and-white  rat  was  chosen  because 
as  a  whole  it  was  more  typical  than  that  of  any  other  individual 
of  the  manner  in  which  the  association  was  formed,  though 
the  time  records  are  lower  than  the  records  of  an  average 
normal  rat.  This  rat,  too,  learned  the  problem  in  fewer  trials 
than  the  average  normal  rat:  indications  of  the  solution  were 
observed  in  the  12th  trial,  in  which  there  seemed  to  appear 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


29 


the  association  between  the  door  and  the  plane.  In  this  trial 
there  were  no  useless  movements.  There  was  little  doubt  that 
in  the  eighteenth  trial  the  association  had  become  fixed. 

The  above  records  of  the  individual  rat  serve  to  call  attention 
to  the  nature  of  the  learning  process  involved  in  this  test.  We 
have  (i)  random  movements;  (2)  the  accidental  successes  from 
which  the  animal  at  first  profits  little;  (3)  the  elimination  of 
useless  movements;  and  (4)  the  completely  established  habit. 

The  elimination  of  useless  movements  in  this  test  is  accom¬ 
plished  in  much  the  same  general  fashion  as  in  tests  of  the 
labyrinth  type.  In  the  former,  however,  the  rat  runs  about  in 
an  open  space,  whereas  in  the  latter  his  pathway  is  restricted 
by  the  side  walls  of  the  galleries.  Therefore  the  random 
movements  in  the  present  case  survive  for  a  longer  time  than 
in  the  labyrinth,  because  there  is  greater  opportunity  for,  and 
a  greater  variety  of,  them.  As  was  stated,  the  rat  usually  goes 
first  to  the  door,  then  about  the  cage  and  to  the  plane  and  back 
again  to  the  door.  Ordinarily  this  routine  continues  until 
about  the  thirtieth  trial,  after  which  the  movements  are  in  a 
great  measure  automatic. 

The  animals,  as  was  stated  earlier,  tend  in  their  habitual 
reactions  to  go  to  the  plane,  thence  to  the  door  by  a  definite 
route,  which  varies  with  the  individual.  An  unusual  turn  in 
leaving  the  plane  to  go  to  the  door  may  so  utterly  confuse 
them,  that  to  run  back  to  the  plane  and  to  start  over  is  the  only 
apparent  manner  of  taking  up  the  trail.  This  is  a  very  fre¬ 
quent  occurrence,  and  among  the  last  trials  is  almost  the  sole 
reason  for  a  high  time  record. 

2.  Statement  of  Results, 
a.  On  Normal  White  Rats. 

The  group  of  normal  white  rats  was  first  tested  upon  the 
problem.^  The  averages  of  the  group,  four  males  and  three 

*  The  problem  box  at  the  beginning  of  this  test  was  not  of  the  same  form  as 
described  here.  The  plane  was  set  immediately  at  the  north  end  of  the  box, 
instead  of  ii  cm.  distant,  and  the  control  cage  was  the  small  one  used  over  Box 
I,  instead  of  the  larger  one  later  used.  The  original  conditions  madethe  prob¬ 
lem  much  easier  of  solution  than  the  experimenter  desired.  Radical  modifica- 


30 


FLORENCE  RICHARDSON. 


females/  are  given  in  Table  V,  following  the  form  of  the  pre¬ 
vious  tables.  The  graphical  representation  of  the  averages 
given  in  Table  V  is  shown  on  Plate  11. 

The  column  showing  the  minimal  time-records  at  each  trial 
indicate  how  quickly  the  problem  can  be  solved.  For  the 
last  ten  trials  the  minimal  time  runs  but  little  over  .03  minutes. 
The  curve  constructed  from  the  group  averages  at  the  succes¬ 
sive  trials  shows  the  second  rise  at  the  third  and  fourth  trials, 
which  is  due  to  the  length  of  time  spent  by  the  rats  in  going 
directly  to  the  door  of  the  box  and  trying  to  push  it  open. 

Table  V. 

Showing  the  average,  the  minimum  and  the  maximum  time-records  of  seven 
normal  white  rats  upon  Problem  II.  The  last  three  columns  show  the  number 
of  animals  whose  records  are  (/)  equal  to  the  average,  (2)  below,  and  (j) 
above  the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

min. 

min. 

min. 

I 

00 

00 

•25 

18.56 

4 

3 

2 

1.42 

.04 

3-49 

4 

3 

3 

2  35 

.04 

9.22 

5 

2 

4 

1-54 

•15 

5-74 

5 

2 

5 

.80 

.  10 

3-03 

6 

I 

6 

•  72 

.09 

2.08 

5 

2 

7 

•95 

.06 

4.40 

6 

I 

8 

■  27 

.08 

•  42 

5 

2 

9 

.20 

•03 

•47 

5 

2 

10 

.20 

.07 

•37 

4 

3 

1 1 

•49 

•63 

1 .20 

4 

3 

tions  were  made  accordingly:  the  plane  was  moved  out  to  a  distance  of  ii  cm. 
and  a  large  control  cage  was  put  over  the  problem  box.  The  rats,  however,  had 
had  two  days  experience  with  the  original  box.  The  above  records  are  all  taken 
from  tests  with  the  modified  box.  It  is  impossible  to  estimate  what  was  carried 
over  from  the  old  situation  to  the  new,  therefore  the  records  may  not  be  quite 
fairly  comparable  to  those  of  the  rats  which  followed;  yet  this  fact  does  not 
detract  from  the  utility  of  the  curve  as  a  whole. 

^  Female  I  learned  to  open  the  door,  not  by  stepping  on  the  plane,  but  by 
tugging  at  the  cord  which  attached  the  plane  to  the  latch.  From  about  the 
thirtieth  trial  she  not  only  tugged  at  the  cord  until  the  door  fell,  but  continued 
to  tug;  so  that  her  time-records  were  too  variable  to  be  included  in  the  average. 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


31 


Table  V. — Continued. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

12 

.  16 

.67 

•47 

6 

I 

13 

•30 

.67 

.62 

3 

4 

14 

.  12 

•57 

•25 

4 

3 

15 

.21 

•67 

•52 

5 

2 

16 

.26 

.08 

1.03 

6 

I 

17 

•13 

•05 

.20 

4 

3 

18 

.07 

•05 

.  10 

5 

2 

19 

•14 

.04 

.67 

6 

I 

20 

.08 

.05 

•33 

A 

3 

21 

14 

■05 

•50 

6 

I 

22 

.09 

.04 

•17 

4 

3 

23 

.12 

.04 

.40 

5 

2 

24 

.08 

•03 

.18 

4 

3 

25 

.05 

•03 

.  10 

2 

5 

26 

.22 

.04 

.62 

4 

3 

27 

13 

•03 

.50 

6 

I 

28 

.  10 

.04 

•27 

5 

2 

29 

•14 

■03 

•33 

4 

3 

30 

.  12 

•03 

•25 

4 

3 

31 

.18 

■03 

•38 

5 

2 

32 

■25 

.06 

1-33 

6 

I 

33 

•14 

.02 

•52 

6 

I 

34 

.08 

.05 

.18 

5 

2 

35 

.11 

.07 

•17 

I 

4 

2 

36 

.  12 

■03 

•25 

4 

3 

37 

.08 

.04 

.  12 

2 

3 

2 

38 

.07 

•03 

.  10 

3 

4 

39 

.07 

.04 

.  12 

I 

3 

3 

40 

.09 

.04 

■23 

I 

5 

I 

41 

.05 

.02 

.08 

I 

3 

3 

42 

.19 

.04 

.88 

6 

I 

43 

.  12 

•03 

•17 

4 

3 

44 

.06 

■03 

.  10 

4 

3 

45 

.  10 

•03 

.20 

I 

3 

3 

46 

.08 

•03 

.  16 

3 

2 

2 

47 

.07 

.04 

.22 

4 

3 

48 

.11 

•03 

.22 

4 

3 

49 

.08 

■03 

.11 

I 

2 

4 

50 

.08 

.06 

•13 

I 

4 

2 

The  following  table  shows  the  percentage  of  minimal  and 
of  maximal  time-records  made  by  each  of  the  rats  in  this  group. 


32 


FLORENCE  RICHARDSON. 


TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 

MADE  BY  INDIVIDUALS. 

Mitiimal.  Maximal. 

percent.  per  cent. 

Male  1 .  12  Male  I .  I2 

Male  II .  40  Male  II .  8 


Male  III .  9 

Male  IV .  8 

Female  II .  ii 

Female  III .  16 

Female  IV .  4 


Male  III .  10 

Male  IV .  12 

Female  II .  8 

Female  III .  31 

Female  IV .  19 


b.  On  Normal  Black-and-White  Rats. 

Table  VI  and  the  curve  on  Plate  II  show  the  records  of  the 
group  of  four  black-and-white  females.  These  rats  were  so 
incessantly  active  that  it  was  often  quite  difficult  to  hold  them 
in  the  hand.  Because  of  this  superabundance  of energy  their 
early  time-records  were  short.  They  gave  evidence  also,  as 
remarked  above,  of  having  acquired  the  association  earlier 
in  the  series  than  the  normal  white  rats,  whose  records  were 
unfortunately  rendered  ambiguous  for  the  comparison. 

After  the  thirty-fifth  trial,  the  rats  received  a  fright,  probably 
due  to  the  odor  of  wild  rats  about  the  cage.  They  were  so 
disturbed  upon  being  introduced  into  the  problem  box  that 
the  final  abandonment  of  the  series  was  necessitated.  Their 
reactions  had  been  practically  constant  in  their  last  fifteen 
trials,  so  that  little  was  lost  to  the  experiment. 

The  following  tabulation  shows  the  percentage  of  minimal 
and  of  maximal  records  of  each  animal. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  RECORDS  OF  EACH 

INDIVIDUAL. 

Minimal.  Maximal, 


per  cent. 

per  cent. 

Female  I . 

.  36 

Female  I . 

.  26 

Female  II . 

.  17 

Female  II . 

.  21 

Female  III . 

.  31 

Female  III . 

.  25 

Female  IV . 

.  16 

Female  IV . 

.  28 

The  percentage  of  maximal  records,  as  indicated  above,  is 
very  evenly  divided  among  the  four  animals.  Females  I  and 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


33 


Table  VI. 

Showing  the  average,  the  minimum  and  the  maximum  time-records  of  four 
black-and-white  females  upon  Problem  II.  The  last  three  columns  show 
the  number  of  animals  whose  records  are  (j)  equal  to  the  average,  (2) 
below,  and  (j)  above  the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

I 

min, 

1-53 

min. 

•78 

min. 

3-07 

3 

I 

2 

1 . 70 

•63 

2-53 

2 

2 

3 

•73 

.22 

1.56 

2 

2 

4 

1 .02 

.70 

1-57 

3 

I 

5 

1.63 

•47 

2.78 

2 

2 

6 

4-17 

•27 

11.80 

3 

I 

7 

1 . 10 

•72 

1-57 

3 

I 

8 

•87 

.18 

1.70 

2 

2 

9 

.90 

■23 

1-50 

I 

I 

2 

10 

•78 

.  10 

1.62 

3 

I 

II 

•37 

.06 

•92 

3 

I 

12 

.48 

•  17 

.96 

2 

2 

13 

.28 

.  10 

•58 

2 

2 

H 

•35 

•25 

•58 

3 

I 

15 

•39 

.05 

.67 

3 

I 

16 

.22 

.11 

•37 

3 

I 

17 

•30 

.08 

.66 

3 

I 

18 

.18 

•13 

•25 

2 

2 

19 

•25 

•  14 

•35 

2 

2 

20 

.  16 

•  13 

.21 

3 

I 

21 

•15 

.07 

•30 

3 

I 

22 

.  12 

.07 

•25 

3 

I 

23 

.  12 

.07 

.20 

3 

I 

24 

.  1 1 

.06 

•23 

3 

I 

25 

.07 

.06 

.08 

2 

2 

26 

•13 

.07 

.18 

I 

2 

I 

27 

•14 

.06 

■37 

3 

I 

28 

•14 

.07 

.28 

3 

I 

29 

■14 

.07 

•30 

3 

I 

30 

.  16 

.09 

•24 

2 

2 

31 

.11 

.05 

•17 

2 

2 

32 

•14 

•05 

•30 

3 

I 

33 

.09 

•05 

•  14 

I 

2 

I 

34 

•13 

.  10 

.  16 

2 

2 

35 

■  14 

.08 

.18 

2 

2 

34 


FLORENCE  RICHARDSON. 


Ill  together  made  two-thirds  of  the  entire  total  number  of 
minimal  records. 


c.  On  Blind  Rats. 

Table  VII  and  the  corresponding  curve  on  Plate  II  show 
similarly  the  average  records  of  six^  blind  rats  on  Problem  II. 

The  behavior  of  the  blind  rats  was  characterized  by  a  lack 
of  eagerness,  although  when  first  introduced  into  the  control 
cage  they  were  most  anxious  to  get  into  the  food  box;  if  they 
were  not  successful  soon  their  activity  abated,  and  random 
movements  characterized  their  efforts.  They  were  slow  in 
forming  a  pathway,  and  in  several  instances  no  definite  path 
was  chosen. 

The  percentage  of  minimal  and  of  maximal  time-records  of 
fort}/-four  trials^  for  each  of  the  blind  rats  is  given  below. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 

MADE  BY  EACH  INDIVIDUAL. 

Ml  nimal.  Maximal. 


per  cent. 

per  cent. 

Female  I . 

.  9 

Female  I . 

.  38 

Female  II . 

.  14 

Female  II . 

.  26 

Female  III . 

.  19 

Female  III . 

.  7 

Female  IV . 

.  29 

Female  IV . 

.  9 

Female  V . 

.  22 

Female  V . 

.  2 

Male  IV . 

.  2 

Male  IV . 

.  18 

d.  On  Anosmic  Rats. 

As  before  stated  all  but  one  of  the  anosmic  rats  died  before 
the  experimentation  had  been  completed.^  The  one  that 
remained  was  set  to  work  on  this  problem.^  He  learned  the 
association  perfectly,  but  invariably  pressed  down  the  plane 

'  Males  1  and  III  had  died  of  an  infection. 

•  Female  II  became  ill,  and  did  not  work  after  the  forty-fourth  trial,  con¬ 
sequently  the  percentage  after  this  trial  is  not  considered.  Male  II  manifested 
a  decided  repugnance  to  approaching  the  plane,  as  the  falling  of  it  had  apparently 
frightened  him;  therefore  he  did  not  learn  the  problem. 

^  The  infection  becan^  apparent  just  after  the  animals  had  completed  their 
work  upon  Problem  I,  and  they  died  almost  immediately  after. 

*  He  was  the  rat  which  gnawed  at  the  wire  in  the  sawdust  box. 


A  STUDT  OF  SENSORY  CONTROL  IN  THE  RAT. 


35 


Table  VII. 


Showing  the  average,  the  mintmum  and  the  maximum  time-records  of  six  blind 
rats  upon  Problem  II.  The  last  three  columns  show  the  number  of  animals 
whose  records  are  (l)  equal  to  the  average,  (2)  below,  and  (j)  above  the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

I 

min. 

1.32 

min. 

•52 

min. 

2.08 

3 

3 

2 

1.47 

■23 

2-75 

4 

2 

3 

4.09 

•52 

12.37 

4 

2 

4 

8-37 

.  12 

45.80 

5 

I 

5 

2-37 

•43 

7-57 

4 

2 

6 

2.12 

•30 

4-03 

3 

2 

7 

3-47 

•47 

8.59 

4 

2 

8 

1.68 

.  12 

4-17 

4 

2 

9 

1-93 

.07 

.62 

4 

2 

10 

1 .70 

.  10 

5-19 

4 

2 

II 

1 .22 

.  12 

4-33 

4 

2 

12 

2.02 

.  12 

8.52 

5 

I 

13 

2.08 

•25 

8.45 

4 

2 

14 

3-34 

•55 

12.03 

5 

I 

15 

2.85 

.22 

12.67 

5 

I 

16 

1 .04 

•15 

2-39 

4 

2 

17 

1. 71 

.  12 

4-13 

4 

2 

18 

•83 

•38 

I  52 

4 

2 

19 

1 .22 

.28 

2.62 

3 

3 

20 

1-55 

•38 

2.33 

3 

3 

21 

1. 18 

.  10 

4-05 

4 

2 

22 

1 .04 

•47 

1.97 

4 

2 

23 

1-35 

.26 

3-50 

4 

2 

24 

1.77 

.28 

4.67 

3 

3 

25 

.96 

.28 

1.87 

3 

3 

26 

III 

.08 

2.42 

3 

3 

27 

.68 

•25 

I  13 

2 

2 

2 

28. 

.48 

•13 

•93 

4 

2 

29 

1 .04 

15 

1. 18 

3 

3 

30 

1. 14 

.18 

1.58 

3 

3 

31 

2.06 

.40 

2.92 

3 

3 

32 

2.80 

•17 

15.12 

5 

I 

33 

.70 

•13 

1 .72 

4 

2 

34 

1. 41 

•17 

3-57 

3 

3 

35 

.08 

•27 

1.85 

3 

3 

36 

1 . 10 

•32 

2.67 

5 

I 

37 

1. 18 

•45 

3-67 

5 

I 

38 

1 .48 

•57 

1 .80 

4 

2 

36 


FLORENCE  RICHARDSON. 


Table  VII. — Continued. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

39 

1-45 

.18 

367 

3 

0 

40 

•97 

•25 

2.88 

4 

2 

41 

■83 

.28 

1.03 

2 

4 

42 

•59 

•17 

I  .  12 

3 

3 

43 

.84 

•25 

I  .  10 

4 

2 

44 

•73 

•25 

2-53 

45 

1 .  1 1 

•13 

2.50 

46 

1. 21 

•17 

3-17 

47 

•75 

•25 

1-75 

48 

.40 

•15 

•85 

49 

•63 

.22 

1 . 10 

50 

.70 

.18 

1.52 

while  gnawing  the  string  which  connected  the  plane  with  the 
box.  When  he  braced  himself  to  gnaw,  the  pressure  of  his 
forefeet  upon  the  plane  was  instrumental  in  pulling  up  the 
latch.  He  continued  to  gnaw  until  he  had  completely  severed 
the  string  from  the  plane.  After  the  thirty-third  trial  he  in¬ 
variably  ran  at  once  to  the  door  when  he  had  finished  biting 
at  the  string  or  plane.  If  he  did  not  find  the  door  open,  he 
went  back  to  the  place  and  his  gnawing,  and  after  another 
effort  scurried  to  the  door  again.  Wire  was  substituted  for 
cord,  whereupon  his  task  was  seemingly  endless,  and  he  varied 
his  procedure  by  dragging  the  plane  about  the  cage.  Table 
VIII  shows  the  records  of  this  rat.  The  time-records  of  the 
later  trials  are  shown  as  they  were  taken,  giving  the  length 
of  time  consumed  by  the  rat  in  different  parts  of  the  cage. 

In  learning  the  problem,  this  rat  did  not  spend  the  greater 
part  of  the  time  in  the  early  trials — as  did  the  rats  possessed  of 
the  sense  of  smell— in  sniffing  at  the  food  through  the  meshes 
of  the  wire  covering  of  the  problem  box.  The  rat  did  lose 
much  time,  however,  in  trying  to  get  into  the  box  by  tugging 
at  the  door. 

For  the  first  six  trials  the  time-records  of  this  anosmic  rat — 
with  the  exception  of  the  second — are  below  one  minute: 
four  of  them  are  below  .50  min.  His  long  time-records  in 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


37 


Table  VIII. 


Showing  the  time  records  of  the  anosmic  rat  on  Problem  II. 


NO.  OF  TRIAi,. 

I.  BEGINS 

GNAWING. 

2.  DOOR  FALLS. 

3.  TIME  FROM 

PLANE  TO  DOOR. 

IN  BOX. 

min. 

min. 

min. 

min. 

I 

■23 

.20 

•43 

2 

•75 

•35 

1 . 10 

3 

.20 

.20 

.40 

4 

•37 

.07 

•44 

5 

•41 

.05 

.46 

6  , 

•33 

•63 

.96 

7 

1.42 

•63 

2.05 

8 

3-33 

1.03 

436 

9 

•25 

•38 

•63 

10 

2.25 

1 .02 

3-27 

II 

.28 

.20 

•48 

12 

10.66 

1-33 

12.00 

13 

.08 

.08 

.  16 

14 

1 .00 

.  12 

1 . 12 

15 

•23 

•35 

.58 

16 

.48 

•58 

1 .06 

17 

1.65 

•73 

2.38 

18 

1.05 

•45 

1.50 

19 

2.92 

.50 

3-42 

20 

.66 

.22 

.88 

21 

2.25 

•30 

2-55 

22 

•83 

•25 

1 .08 

^3 

•33 

.08 

.41 

24 

.20 

•17 

•37 

25 

1.25 

•13 

I  38 

26 

1-33 

•32 

1.65 

27 

I  25 

.28 

1-53 

28 

.22 

•13 

•35 

29 

•32 

•48 

.80 

30 

1.03 

•25 

1.28 

3^ 

1.80 

•32 

2.12 

32 

•92 

•25 

1. 17 

33 

2.12 

•53 

2.67 

34 

•83 

•15 

•98 

35 

.22 

•50 

•72 

36 

•50 

.20 

.70 

37 

.06 

1.63 

•03 

1 .66 

38 

.20 

•85 

.05 

.90 

39 

.08 

1.42 

•05 

1-45 

40 

•05 

•50 

•03 

•53 

41 

•03 

1 .08 

•03 

1 .  1 1 

42 

.18 

1 .40 

.08 

1 .48 

43 

.07 

.67 

•03 

.70 

44 

.20 

•83 

■03 

•85 

•03 

•63 

.02 

.65 

38 


FLORENCE  RICHARDSON. 


the  later  trials  were  due  to  his  gnawing  propensities.  The 
time  which  he  spent  in  going  from  the  entrance  to  the  plane, 
or  from  the  plane  to  the  food  box  was  not  longer  than  that  of 
the  average  normal  rat.  In  the  last  nine  trials  the  average 
time  from  entrance  to  plane  is  .10  min.,  and  from  plane  to 
door  .04  min.  Disregarding  the  time  spent  in  gnawing,  his 
average  time  would  be  .14  min.,  for  these  trials;  which  may 
by  a  glance  at  the  curves  be  seen  to  be  but  little  longer  than 
the  average  time-records  of  the  normal  rat,  and  shorter  than 
the  maximal  time-records  of  that  group. 

J.  Effect  on  Rats  of  Changing  Position  of  Plane  go°  to  Right. 

After  the  group  of  normal  white  rats  had  completed  Tis 
series,  the  position  of  the  plane  was  changed,  being  placed 
east  of  the  box,  instead  of  north  as  before.  The  reactions  of 
the  animals  had  become  practically  habitual  before  the  change 
was  made.  It  was  thought  that  the  change  in  conditions 
might  bring  out  two  facts  regarding  the  behavior  of  the 
animal:  (i)  The  nature  of  the  sensory  control  in  the  habitual 
act;  (2)  the  nature  of  the  sensory  data  by  means  of  which  the 
modified  reaction  which  is  necessary  under  the  changed  con¬ 
ditions  is  built  up. 

Since  the  rats  in  this  series  were  put  always  into  the  cage 
from  the  east,  their  established  pathway  carried  them  within 
two  or  three  inches  of  the  longer  side  of  the  plane.  Each  of 
the  four  males  was  tried  in  turn,  and  each  went  directly  to  the 
old  position  of  the  plane,  then  ran  to  the  door.  One  of  them. 
Rat  III,  seemed  confused  at  not  finding  the  plane  in  the 
usual  position.  The  other  three  went  to  the  food  box  as  though 
not  missing  the  link  in  the  series.  Their  confusion  began  at 
the  door.  Each  rat,  after  running  about  in  a  seemingly  aim¬ 
less  manner  for  a  few  seconds,  struck  the  plane  and  the  door 
fell.  Rat  I  could  not  seem  to  find  the  way  to  the  door,  even 
though  something  connected  with  the  falling  of  the  plane  made 
him  frantically  eager  to  get  back  to  the  box.  He  finally 
went  over  the  box.  On  the  third  trial  he  proceeded  slowly 
and  kept  his  nose  to  the  floor  (discovering  the  plane  by  touch  .^). 
From  the  fourth  to  the  ninth  trial  he  passed  over  the  plane 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


39 


directly  on  his  way  to  the  door.  On  both  the  ninth  and  tenth 
trials,  he  reverted  to  his  old  habit  of  going  at  once  to  the  orig¬ 
inal  position  of  the  plane  on  the  north.  Rat  II  reverted  to 
the  old  habit  similarly  in  the  ninth  trial.  Rat  III  went  to 
the  door  first,  except  on  the  seventh  and  ninth  trials  when  his 
route  accidentally  took  him  far  enough  south  to  touch  the 
plane.  The  slight  contact  seemed  to  give  him  immediate 
orientation,  for  he  ran  across  the  plane  and  to  the  door  at  once. 

Rat  IV  was  the  least  confused.  He  ran  to  the  old  position 
but  did  not  go  to  the  door.  Instead,  he  began  wandering 
about  and  strayed  across  the  plane  in  a  seemingly  haphazard 
fashion,  but  the  instant  it  fell  the  old  habit  reasserted  itself 
and  he  dashed  off  to  the  door.  At  the  second  trial  he  went 
directly  across  the  plane  to  the  door.  All  his  other  trials  were 
almost  precisely  like  his  second.  His  records  were  quite  phe¬ 
nomenally  quick  after  the  first  trial,  not  going  above  .03  min.‘ 

This  test  furnished  some  evidence  upon  the  two  facts  sought 
for,  i.  e.,  the  sensory  avenues  of  control  in  the  habitual  act,  and 
the  sensory  avenues  of  control  in  the  process  of  readjustment. 
The  habitual  act  seems  to  be  carried  out  by  means  of  the  guid¬ 
ance  of  kinaesthetic  impressions.  The  rats  traversed  the  old 
pathway  even  when  such  movements  did  not  lead  to  the  suc¬ 
cessful  solution  of  the  problem.  The  old  coordination  broke 
down  apparently  in  the  case  of  these  animals  when  they  found 
the  door  closed;  the  fourth  (Rat  HI)  seemed  to  become  con¬ 
fused  in  not  getting  the  ‘cue’  at  the  plane  itself.  The  question 
of  the  probable  nature  of  the  cue  is  discussed  later  in  the  sec¬ 
tion  (p.  40). 

*  The  case  of  Rat  IV  seems  anomalous.  The  records  bear  evidence  to 
the  fact  that  the  pathway  of  this  rat  in  solving  the  original  problem  was 
variable.  In  seven  out  of  the  ten  trials  just  preceding  the  change  in  the  appara¬ 
tus,  the  animal  went  first  to  the  door,  then  to  the  plane.  In  the  first  trial  after 
the  change,  he  departed  from  his  former  custom  of  going  first  to  the  door,  and 
instead  went  direct  to  the  plane.  His  confusion  at  that  point  was  no  greater 
than  he  had  often  previously  displayed  in  picking  up  the  trails.  On  the  second 
trial  and  on  all  thereafter,  he  resumed  his  old  habit  of  going  at  once  to  the  door; 
the  result  of  which  was  that  he  threw  the  plane  en-route  as  it  was  directly  in  his 
path  from  the  entrance  of  the  cage  to  the  door  of  the  food  box.  This  explanation 
accounts  for  the  seeming  variation.  It  was  simply  a  case  in  which  the  failure 
of  the  rat  to  acquire  a  stereotyped  mode  of  response  to  the  old  situation  made 
the  adjustment  to  the  new  situation  less  difficult. 


40 


FLORENCE  RICHARDSON. 


The  new  coordination  necessary  in  the  readjustment  to  the 
changed  situation  is  built  up  on  the  sensory  data  by  means 
of  which  the  plane  becomes  the  stimulus  to  the  further  coor¬ 
dination  involved  in  running  from  the  plane  after  it  has  fallen 
directly  to  the  door  of  the  food  box.  In  these  cases  [/.  e., 
the  inclined  plane]  the  basis  seems  to  be  that  afforded  by 
touch.  Contact  with  the  plane  was  doubtless  the  evidence  of 
its  presence.  Had  some  distance  sense  factor  such  as  vision 
given  the  cue,  it  would  seem  that  the  animal  would  have  had 
less  difficulty  in  finding  the  plane  in  the  new  position  which 
was  at  such  a  short  distance  from  the  old  position.  It  was 
only  when  they  came  in  contact  with  the  plane  that  some  sen¬ 
sory  impulse  connected  with  its  fall  set  off  the  old  association 
and  they  would  dash  to  the  door  of  the  box.  The  new  path¬ 
way  was  easily  learned,  though,  as  remarked  above,  not  closely 
adhered  to  as  three  of  the  rats  on  later  trials  made  errors  in 
favor  of  the  old  pathway. 

It  had  been  a  part  of  the  plan  of  the  work  to  further  modify 
this  test,  but  it  was  found  later  that  the  conditions  of  the 
learning  process  had  not  been  sufficiently  well  controlled.  In 
a  test  of  this  kind  the  rats  should  have  learned  the  association 
in  an  environment  every  part  of  which  was  equally  illuminated, 
so  that  a  change  in  the  apparatus  would  involve  no  change  in 
brightness  values  in  different  portions  of  the  field.  The  con¬ 
trol  cage  should  have  been  lined  with  canvas  or  other  opaque 
material  so  as  to  preclude  the  possibility  of  orientation  by  means 
of  distance  sense  factors.  On  this  account  a  test  involving 
such  modifications  as  have  been  here  made  are  not  conclusive. 
The  results  are  suggestive;  and  if  the  test  were  properly  con¬ 
trolled  it  would  be  of  value  in  isolating  the  different  sense 
factors  which  function  in  forming  the  association. 

A  problem  of  especial  interest  which  arose  in  carrying  out 
the  above  work  is  that  of  the  sensory  avenue  by  means  of  which 
the  rat  obtains  the  cue  for  the  run  to  the  door  after  the  plane 
has  fallen.  In  the  early  trials  of  the  test  it  seemed  quite  suffi¬ 
cient  for  the  rat  merely  to  run  past  a  certain  point  on  the 
floor  of  the  cage.  Indeed,  many  rats  never  appear  to  get 
beyond  this  method  of  reacting.  But  occasionally  a  rat  hesi- 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


41 


tates  at  the  plane  apparently  until  he  gets  a  cue  that  the 
door  has  fallen  inward.  In  such  instances  the  cue  may  be: 
(i)  The  sound  of  the  falling  door;  (2)  the  molecular  vibrations 
(tactual  impressions)  set  up  in  the  wood  by  the  door  as  it  falls 
upon  the  floor  of  the  cage;  (3)  the  jar  (kinaesthetic  and  pos¬ 
sibly  static)  of  the  falling  plane. 

Male  III  was  an  animal  which  did  not  seem  to  require  such 
a  cue.  Several  times  in  the  last  ten  trials  this  animal  would 
run  to  a  position  about  one  inch  west  of  the  plane,  rear  up 
slightly,  and  assume  the  crouching  attitude  which  he  had  been 
accustomed  to  assume  on  the  plane  itself  and  would  then  dash 
back  to  the  door.  He  had  thus  gone  through  all  the  move¬ 
ments  of  throwing  the  plane,  except  that  he  had  not  performed 
them  on  the  plane.  He  was  completely  confused  when  he  found 
the  door  closed.  This  rat  at  least,  evidently  oriented  himself 
according  to  the  relative  position  of  the  plane.  The  tactual 
element  in  the  experience  seemed  of  no  value  while  the  kin- 
aesthetic  experience  of  raising  the  forepart  of  the  body  and 
lowering  it  was  apparently  the  esssential  feature.  This  kin- 
aesthetic  series  was  sufficient  to  set  off  the  sequent  coordinations. 
The  failure  of  the  animal  to  react  to  the  plane  itself  when 
almost  touching  it  and  when  to  all  appearances  attempting  to 
react  to  it,  is  typical  of  the  earlier  trials  of  practically  all  of  the 
rats.  There  is  no  evidence  whatever  that  the  rat  perceived 
the  plane  or  that  the  plane  comes  to  be  an  isolable  portion  of 
the  problem  box  situation.  A  rat,  when  attempting  to  get 
into  the  food  box,  runs  around  the  box  in  varying  circles. 
In  one  of  these  circles  he  runs  over  the  plane  and  when  he  hurries 
back  to  the  door,  as  he  does  after  every  peregrination,  he  finds 
it  open.  Many  such  trials  are  necessary  before  he  establishes 
a  pathway  which  includes  in  its  course  the  crossing  of  the 
plane.  This  seems  to  indicate  that  the  reaction  of  the  animal 
to  the  plane  is  determined  by  kinaesthetic  data  and  that  the 
kinaesthetic  experience  at  this  point  is  the  stimulus  for  the 
further  movement,  namely,  that  of  turning  to  take  up  the 
pathway  to  the  door. 

On  the  other  hand  the  behavior  of  Male  H  of  the  same  group 
indicates  a  different  kind  of  series  of  stimulations  at  the  plane. 


42 


FLORENCE  RICHARDSON. 


His  path  led  him  out  upon  the  plane,  rather  than  across  it. 
On  his  forty-fourth,  forty-eighth,  forty-ninth  and  fiftieth  trials 
he  crouched  near  the  margin  of  the  plane  nearest  the  cage, 
but  as  he  was  not  far  enough  away  from  the  inner  margin,  his 
weight  was  not  sufficient  to  press  down  the  plane,  and  conse¬ 
quently  he  could  get  no  report.  He  then  took  another  step 
further  out  and  waited.  Usually  the  door  fell  after  his 
second  step.  It  happened  once  on  the  forty-ninth  trial  that 
a  third  step  was  necessary  to  press  down  the  plane.  When 
this  step  had  been  taken,  and  the  door  had  fallen,  he  hurried 
off  to  the  food  box. 

It  is  not  easy  to  postulate  just  what  happened  in  the  case  of 
this  rat.  It  is  evident  that  some  form  of  sensory  data,  probably 
auditory,  combined  possibly  with  tactual,  kinaesthetic  and 
organic,  gave  the  cue  to  the  succeeding  coordinations. 

4.  Summary. 

a.  Average  Time-records  for  the  Total  Series. 

The  average  of  the  total  time  consumed  both  by  the  indi¬ 
viduals  and  the  groups  is  given  below.  The  group  averages 
are  given  only  for  the  first  thirty-five  trials,  by  reason  of  the 
fact  that  the  group  of  black-and-white  rats  were  unable  to 
finish  the  series  of  fifty  trials. 

TABLE  SHOWING  THE  GROUP  AVERAGE  OF  THE  TOTAL  TIME  (tHIRTY-FIVE  TRIALS) 
CONSUMED  BY  NORMAL  AND  BY  DEFECTIVE  RATS  IN  LEARNING  PROBLEM  II. 

Average  by  Groups 


min. 

min- 

Normal  White. . 

.48  Blind.. 

1.48 

Normal  Black-and-White. .  .  . 

•  -49 

TABLE  SHOWING 

INDIVIDUAL 

AVERAGES  OF  THE 

TOTAL 

time(35 

TRIALS 

)  CON- 

SUMED  BY  NORMAL  AND  BY  DEFECTIVE  RATS 

IN  LEARNING  PROBLEM 

II. 

Normal 

White. 

Normal  Black-and-White 

Blind. 

mtn. 

min. 

min. 

Male  I . 

. 31 

Female  I . 

•77 

Female 

I . 

1.56 

Male  II . 

. 84 

Female  II . 

•44 

Female 

II . 

1.67 

Male  III . 

. 26 

Female  III . 

■52 

Female  III . 

1. 14 

Male  IV . 

. 71 

Female  IV . 

■51 

Female 

IV  ... . 

I  .02 

Pern  ale 

V . 

.60 

Female  II.... 

. 42 

Male  IV 

•77 

Female  III .  .  . 

. 43 

Female  IV.  .  .  . 

. 40 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


43 


fr  Tria/j. 


44 


FLORENCE  RICHARDSON. 


There  is  practically  no  difference  in  the  averages  of  the 
group  of  the  white  and  of  the  black-and-white  animals.  The 
average  of  the  group  of  blind  rats  is  much  greater  than  that 
of  the  normal  rats. 

The  variation  among  the  averages  of  the  individuals  is  con¬ 
siderable.  The  high  records  of  the  normal  white  Males  II 
and  IV,  were  due  to  high  time-records  in  the  first  ten  trials. 
The  averages  of  the  normal  white  females  are  all  lower  than 
the  lowest  of  those  of  the  black-and-white  group.  Blind  F emales 
IV  and  V  and  blind  Male  V,  made  averages  lower  than  the 
maximum  individual  records  of  either  the  normal  white  or 
the  black-and-white  groups.  There  is  greater  variation  among 
individuals  of  this  blind  group  than  among  those  of  any  other 
group. 

b.  Average  Time-Records  by  Groups  of  Ten  Trials. 

The  following  tables  show  the  averages  of  the  records  of 
the  series  by  groups  of  ten  trials  each.  The  averages  are  given 
for  the  individuals,  and  for  the  groups.  The  starred  records 
show  those  instances  in  which  the  minimal  record  for  a  series 
of  ten  was  reached  before  the  last  series  of  ten. 


Normal  White  Rats. 


INDIVIDUALS. 

GROUP. 

TRIALS. 

MALE  I. 

MALE  II. 

MALE  III. 

MALE  IV. 

nun. 

mill. 

mtn. 

nitn. 

I-IO 

.64 

2.67 

.62 

2.27 

I  1-20 

•24 

•17 

.08* 

.08 

21-30 

.  10* 

.05* 

.05* 

31-40 

.  1 1 

•05 

.09 

.  10 

41-50 

.07 

.08 

13 

.09 

FEMALE  I. 

FEMALE  II. 

FEMALE  III. 

FEMALE  IV. 

min. 

I-IO 

I  .  16 

•79 

.96 

1.44 

1 1-20 

.  10 

•43 

•24 

.19 

21-30 

.  12 

•27 

■N 

•13 

31-40 

.09* 

.28 

.09 

.  1 1 

41-50 

•17 

■17 

.08 

.  10 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


45 


Black-and- White  Rats. 


FEMALE  I. 

FEMALE  II. 

FEMALE  III. 

FEMALE  IV. 

I-I 

2.28 

1.03 

I. 19 

I.  19 

1.42 

11-20 

•14 

•25 

•47 

■32 

.29 

21-30 

.  12* 

•13 

.08* 

.18 

■13 

31-35 

.  16 

•13 

.09 

.09 

.  12 

Blind  Rats. 


FEMALE  I. 

FEMALE  II. 

FEMALE 

III. 

FEMALE 

IV. 

FEMALE 

V. 

MALE 

IV. 

GROUP. 

I-IO 

2.96 

.51* 

1.23 

8-34 

I  .  12 

2.94 

2.85 

11-20 

4.50 

•74 

1.23 

•69 

•77 

2.68 

1.77 

21-30 

1-43 

2.00 

I.  13* 

.29* 

.61 

1 .00 

I  .07* 

31-40 

2.81 

1.99 

I  .28 

.46 

•75 

.84* 

I  35 

41-50 

I .  II 

1.28 

•40 

•57 

7.80 

2.23 

Here,  as  in  Problem  I,  many  rats — in  this  case  ten  out  of 
a  total  of  seventeen  animals — made  their  lowest  averages  before 
the  last  ten  trials  of  the  series.  This  peculiarity  is  especially 
noticeable  in  the  above  records  of  blind  Female  II  whose  first 
group  of  ten  averaged  considerably  less  than  any  later  ten. 

The  blind  group  is  the  only  group  whose  total  average  shows 
the  minimal  average  by  ten  near  the  middle  of  the  series. 

c.  Comparison  of  the  Different  Groups. 

The  curve  showing  the  average  time-records  of  the  group  of 
normal  white  rats  is  lowest  at  the  first  trial,  from  the  fifth  to 
the  eleventh  trials,  and  from  the  seventeenth  to  the  twenty- 
fifth  inclusive. 

The  curve  of  the  black-and-white  rats  has  a  very  pronounced 
rise  at  the  sixth  trial;  otherwise  it  is  more  regular  in  contour 
than  that  of  the  group  of  the  normal  white  rats. 

The  curve  representing  the  blind  rats  is  exceedingly  high  and 
irregular  though  at  the  first  trial  it  is  lower  than  any  other,  and 
at  the  second  trial  is  below  that  of  the  black-and-white  rats 
and  but  little  above  that  of  the  normal  white  rats.  From  the 
eighth  trial  this  curve  does  not  descend  to  the  level  of  the 
curve  of  the  normal  animal. 


46 


FLORENCE  RICHARDSON. 


C.  TESTS  ON  PROBLEM  BOX  III. 

I.  Description  of  Apparatus,  and  of  the  Learning  Process. 

The  third|problem  box  submitted  to  these  same  groups  of 
rats  was  the  familiar  one  necessitating  the  raising  of  a  latch. 
As  in  the  two  previous  problems,  the  animal  enters  the  box 
for  food.  The  box  consists  of  a  wooden  frame,  14.25  cm.  in 
height,  20  cm.  in  length  and  20  cm.  in  breadth.  The  frame 
is  covered  with  wire  netting  of  one  centimeter  mesh.  The 
spring  door,  6.25  cm.  high  and  10  cm.  wide,  is  so  fastened  to 
the  lower  left  hand  corner  of  one  side  of  the  box,  that  when  the 
latch  which  holds  the  door  in  place  is  raised,  the  door  opens 
outward.  (See  figure  3.) 


The  control  cage  which  was  placed  over  the  box  is  the  same 
size  as  was  used  over  Box  I.  A  morsel  of  cream  cheese — 
always  of  one  commercial  brand  to  insure  constancy  of  taste 
and  of  odor— was  rubbed  on  the  back  of  the  latch  at  the  begin¬ 
ning  of  the  series  of  trials.  The  combined  taste  and  odor 
served  to  attract  the  interest  of  the  rat,  the  effect  of  which  was 
to  lower  the  absolute  time  records  of  the  first  trials.  The  use 
of  this  device  does  not  alter  the  general  form  of  the  learning 
curve,  nor  influence  the  later  time  records. 

The  unusual  coordinations  involved  in  this  test  are  those 
connected  with  finding  the  door  and  raising  the  head  to  lift 
the  latch.  The  animal  may  lift  the  latch  either  with  its  teeth, 
snout  or  claws.  The  rapidity  of  the  solution  depends  in  the 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


47 


first  few  trials  largely  upon  the  particular  type  of  movement 
adopted  by  the  rat  in  opening  the  latch.  The  animal  which 
lifts  the  latch  with  its  snout  is  likely  to  make  the  shortest  time- 
record,  in  view  of  the  fact  that  this  movement  requires  fewest 
muscular  coordinations. 

The  diary  notes  are  given  as  the  most  concise  and  satis¬ 
factory  description  of  the  learning  process. 


Notes  on  the  Behavior  of  Normal  Male  Rat  III  tn  Learning  Problem  III- 


TRIAL. 

6/2/06 

I 

The  spring  interests  him;  stands  on  his  hind  legs  and  pulls 
it  continually.  While  working  at  spring,  presses  down 
inner  end  of  latch.  Crawled  in  over  top  of  door. 
Time:  2.20  min. 

2 

Same  procedure  as  above,  but  animal  more  active. 
Time:  .13  min. 

3 

Repeated  above:  Time:  1.25  min. 

6/3/06 

4 

Leaves  spring  to  gnaw  at  latch;  pushes  down  inner  end 
of  latch  as  before.  Time:  .13  min. 

5 

Raises  latch  with  teeth.  Time:  .25  min. 

6 

As  above.  Goes  in  over  door  each  time.  Time:  .12  min. 

This  particular  rat  crawled  either  over  or  under  the  door 
in  entering  the  food  box  until  the  end  of  the  series.  Most 
of  the  rats  discovered  the  easier  method  of  entrance,  and  a 
number  of  them  learned  to  raise  the  latch  from  the  left,  and 
saved  themselves  the  annoyance  of  a  blow  from  the  opening 
door.  In  a  number  of  instances  the  rats  became  wary  about 
entering  the  box  on  account  of  having  been  struck  by  the  door. 
Many  long  time-records  near  the  beginning  of  the  series  are 
to  be  explained  in  this  manner.  Individual  variations  in  the 
animals’  methods  of  solving  this  problem  are  more  noticeable 
here  than  in  any  of  the  other  problems. 

2.  Statement  of  Results, 
a.  On  Normal  White  Rats. 

Table  IX  and  the  curve  on  Plate  III  show  the  averages  of 
the  time-records  of  the  group  of  normal  white  rats  upon  this 
problem. 


48 


FLORENCE  RICHARDSON. 


The  group  at  this  time  consisted  of  four  males  and  two 
femalesd 

Table  IX. 


Showing  the  average,  the  minimum  and  the  maximum  time-records  of  six  normal 
white  rats  on  Problem  III.  The  last  three  columns  show  the  number  of 
animals  whose  records  are  (l)  equal  to  the  average,  (2)  below,  and  (j)  above 
the  average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

I 

min. 

5.72 

min. 

1.87 

min. 

9.48 

3 

3 

2 

•32 

.08 

•55 

3 

3 

3 

•33 

.02 

1.25 

5 

I 

4 

•  17 

.  10 

.21 

2 

4 

5 

.29 

.08 

•87 

4 

2 

6 

.22 

.  12 

•37 

4 

2 

7 

.09 

.04 

•  14 

3 

3 

8 

.09 

.05 

•15 

I 

3 

2 

9 

.06 

•03 

.08 

3 

3 

10 

.06 

•03 

.08 

4 

2 

1 1 

.07 

•05 

.  II 

I 

3 

2 

12 

•05 

•03 

.07 

2 

2 

2 

13 

•05 

.02 

.07 

3 

3 

14 

.05 

.04 

.06 

2 

3 

I 

15 

•05 

•03 

.08 

5 

I 

These  rats  did  not  discover  the  door  in  the  first  trial;  but 
at  the  second  they  went  almost  immediately  to  it  and  bit  and 
clawed  at  the  latch  and  spring  with  great  energy.  By  the 
end  of  the  series,  each  rat  had  learned  to  lift  the  latch  with 
its  snout,  and  most  of  them  raised  the  latch  from  the  outer 
margin  and  were  thus  out  of  the  way  of  the  door  when  it  flew 
open.  The  individual  records  are  very  uniform.  At  the 
fifteenth  trial  the  coordinations  were  perfect  and  had  become 
habitual.  The  experiments  were  therefore  discontinued. 

’This  group  has  been  reduced  in  numbers.  Female  III  died,  and  Female  I 
who  was  slow  in  Problem  I,  slower  in  II,  and  very  slow  in  the  present  problem 
made  such  uniformly  poor  records  that  they  were  omitted  in  the  average,  as  they 
represented  a  very  marked  variation.  She  made  the  maximum  time-record  in 
every  trial.  Her  time-records  are  given  and  discussed  in  the  section  on  individ¬ 
ual  variations. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


49 


The  following  table  shows  the  percentage  of  maximal  and 
of  minimal  time-records  made  by  each  animal. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 


MADE  BY 

Minimal. 

per  cent. 


Male  1 .  46 

Male  II .  10 

Male  III .  10 

Male  IV .  34 

Female  II .  o 

Female  III .  o 


EACH  INDIVIDUAL. 

Maximal. 

per  cent. 


Male  I . 

.  0 

Male  II . 

.  0 

Male  III . 

.  13 

Male  IV . 

.  27 

Female  II . 

.  40 

Female  III . 

.  20 

Neither  of  the  two  females  made  a  minimal  record  during 
the  series,  and  neither  Male  I  nor  Male  II  made  a  maximal 
record  during  the  series. 


b.  On  Normal  Black-and-White  Rats. 

This  group  had  also  been  reduced  in  number.  Females  I 
and  II  died  at  the  end  of  tests  upon  Problem  Box  II.  Table 
X  and  the  curve  on  Plate  III  show  the  records  of  the  two  remain¬ 
ing  animals. 

Table  X. 

Showing  the  Average  T  ime-records  of  Two  Black-and-White  Rats  on  Problem  III . 


average. 

NO.  OF  TRIAL. 

AVERAGE 

min. 

min. 

•99 

15 . 

.04 

•49 

16 . 

.07 

.  12 

17 . 

.04 

.29 

18 . 

.04 

.09 

19 . 

.06 

.  II 

20 . 

.08 

.07 

21 . 

.09 

.04 

22 . 

•05 

.08 

23 . 

.04 

.06 

24 . 

.04 

•14 

25 . 

.04 

.04 

26 . 

.04 

•05 

27 . 

•03 

.07 

28 . 

•05 

NO.  OF  TRIAL. 


1. 

2. 

3- 

4- 

5- 
6. 

7- 

8. 

9- 

10. 

1 1 . 
12. 

13- 

H- 


5° 


FLORENCE  RICHARDSON. 


The  records  of  these  two  rats  are  very  low,  and  very  uniform. 
The  first  successes  were  achieved  in  remarkably  short  time, 
all  of  the  averages  being  below  one  minute.  In  the  later  trials, 
each  rat,  in  its  eagerness  to  get  to  the  door,  sometimes  dashed 
past  it,  and  went  on  around  the  box,  thus  lengthening  the 
time-record. 

The  percentage  of  minimal  and  of  maximal  time-records 
made  by  each  rat  in  the  group  is  shown  below. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 

MADE  BY  EACH  INDIVIDUAL. 

Minimal.  Maximal. 

percent.  percent. 

Female  III .  30  Female  III .  70 

Female  IV .  70  Female  IV .  30 

c.  On  Blind  Rats. 

The  behavior  of  the  blind  rats  was  strikingly  at  variance 
with  that  of  the  normal  rat  in  this  problem.  Their  time- 
records  were  long  and  inconstant.  Practically  all  of  the  rats 
suffered  an  emotional  shock  from  the  quick  opening  of  the  door 
when  the  latch  was  raised.  The  blind  animals  were  not  alone 
in  receiving  a  fright  at  the  blow  of  the  ,door.  One  normal 
rat  became  so  cautious  in  his  attempts  to  raise  the  latch  that 
his  efforts  in  going  up  to  the  latch,  springing  back,  stepping 
up  cautiously  again,  and  again  rebounding,  came  to  be  ludic¬ 
rous  in  the  extreme.  On  one  occasion  the  unsuccessful  efforts 
of  a  blind  rat  to  raise  the  latch  were  counted.  Thirty-three 
times  she  approached  the  latch  and  thirty-two  times  she  re¬ 
coiled  like  a  tight  spring!  Only  at  the  thirty-third  attempt 
did  she  exert  enough  pressure  to  lift  the  latch,  and  when  the 
door  flew  open  she  seemed  paralyzed  with  fright  for  several 
seconds,  and  did  not  attempt  to  enter  the  box.  When  she 
finally  entered  she  caught  up  a  mouthful  of  food  and  ran  out¬ 
side  to  devour  it.  This  state  of  high  emotional  tension  is 
one  cause  of  their  poor  time-records,  particularly  in  the  early 
trials. 

The  following  table.  Table  XI,  and  the  curve  on  Plate  III 
show  the  time-records  of  the  group. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


51 


Table  XI. 

Showing  the  average,  the  minimum  and  the  maximum  time-records  of  three  blind 
rats  on  Problem  III.  The  last  three  columns  show  the  number  of  animals 
whose  records  are  (l)  equal  to  the  average,  (2)  below,  and  (5)  above  the 
average. 


NO.  OF 

TRIAL. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

I. 

2. 

3- 

I 

min. 

7-32 

min. 

3-95 

min. 

923 

I 

2 

2 

3-93 

.  18 

937 

2 

I 

3 

•57 

.28 

■75 

I 

2 

4 

2-59 

•45 

6.07 

2 

I 

5 

3-79 

•92 

7.28 

2 

I 

6 

I  .qo 

.22 

495 

2 

I 

7 

1.78 

•15 

4.65 

2 

I 

8 

■95 

■35 

1 .70 

2 

I 

9 

I  31 

.48 

2-35 

2 

I 

10 

•92 

.  12 

1.42 

I 

2 

II 

•53 

•38 

■77 

2 

I 

12 

•53 

•17 

.80 

I 

2 

13 

.60 

.20 

■78 

I 

2 

14 

•30 

.  12 

•34 

I 

2 

15 

.20 

.12 

.28 

2 

I 

16 

•30 

•25 

■35 

I 

I 

I 

17 

.19 

.  10 

•30 

2 

I 

18 

•17 

.11 

•23 

I 

2 

19 

•51 

.20 

1-13 

2 

I 

20 

.19 

.07 

•30 

I 

.2 

21 

.28 

.  12 

•37 

I 

2 

22 

■30 

.22 

•45 

2 

I 

23 

.21 

.20 

•35 

2 

I 

24 

23 

.  10 

•30 

I 

2 

25 

•25 

.  12 

•35 

I 

2 

26 

.18 

•13 

•25 

2 

I 

27 

•27 

•23 

-.33 

2 

I 

28 

■H 

.08 

•25 

2 

I 

29 

.18 

.  10 

.28 

2 

I 

30 

.28 

•17 

.38 

I 

I 

I 

31 

■34 

.22 

•45 

I 

2 

32 

.26 

.  12 

•35 

I 

2 

33 

.19 

.08 

•35 

2 

I 

34 

•36 

.  10 

•83 

2 

I 

35 

•30 

•17 

•43 

I 

I 

I 

36 

•29 

■15 

•47 

2 

I 

37 

■44 

.  10 

•72 

I 

2 

38 

•33 

.08 

•55 

1 

2 

39 

•27 

•05 

.40 

I 

2 

40 

•23 

.18 

.26 

I 

1 

2 

52 


FLORENCE  RICHARDSON. 


The  blind  rats  were  slow  in  attaining  their  first  successes, 
and  in  establishing  a  pathway  from  the  entrance  of  the  cage  to 
the  door  of  the  food  box.  Several  rats  did  not  establish  a 
definite  route  even  after  forty  trials.  In  these  cases  the  behavior 
of  the  animal  throughout  the  test  suggested  the  random  activ¬ 
ity  of  early  trials. 

The  table  given  below  shows  the  percentage  of  minimal 
and  of  maximal  time-records  made  by  each  rat. 

TABLE  SHOWING  PERCENTAGE  OF  MINIMAL  AND  OF  MAXIMAL  TIME-RECORDS 

MADE  BY  EACH  INDIVIDUAL. 

Maximal. 

percent.  per  cent. 

51  Male  IV .  23 

34  Female  IV .  27 

15  Female  V .  50 

d.  On  Anosmic  Rat. 

The  one  remaining  anosmic  rat  was  put  to  work  upon  the 
problem.  He  learned  to  open  the  door  at  once,  but  rather 
than  enter  the  food  box  gratified  himself  by  gnawing  away 
the  wooden  latch.  He  had  apparently  established  the  asso¬ 
ciation  by  the  fifth  trial.  His  time-records  are  almost  value¬ 
less,  however,  being  a  measure,  not  primarily  of  the  length 
of  time  it  took  him  to  open  the  door  of  the  food  box  and  enter 
but  of  the  time  he  gave  himself  for  the  demolition  of the  latch. 

3.  Effect  on  Rats  of  Changing  Position  of  Box  and  Cage. 

After  three  black-and-white  males  had  learned  this  problem, 
the  experimenter  changed  the  position  of  both  the  control 
cage  and  the  problem  box.  In  the  original  experiment  the 
entrance  to  the  cage  was  on  the  east,  and  the  door  of  the  prob¬ 
lem  box  upon  the  south.  After  the  change,  the  door  of  the 
cage  was  to  the  north,  and  the  door  of  the  problem  box  was 
to  the  east.  The  relative  positions  of  the  entrance  of  the  cage 
to  the  door  of  the  problem  box  thus  remained  the  same;  only 
the  absolute  directions  had  been  changed.  The  cage  and  the 


Minimal. 

Male  IV . 

Female  IV . 

Female  V . 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


53 


enclosed  problem  box  had  been  rotated  through  an  angle  of 
90°.  The  floor  of  the  cage  was  of  galvanized  iron  sheeting, 
and  was  turned  with  the  entire  apparatus. 


A  B 

Fig.  4. 


Note  The  dotted  line  shows  the  direct  pathway  from  the  entrance  of  the 
cage  to  the  door  of  the  problem  box.  Rats  which  have  established  a  regular 
pathway  use  the  one  indicated  in  A.  The  dotted  line  in  B,  shows  the  lengthened 
pathway  the  rats  followed  after  the  problem  box  and  cage  had  been  turned. 


Three  normal  black-and-white  males  had  learned  the  prob¬ 
lem.  Their  time-records  had  been  reduced  to  .03  min.,  i.  e., 
practically  to  the  reaction  time  of  the  animal. 

The  appended  diary  notes  describe  the  behavior  of  the 
animals  very  clearly. 


54 


FLORENCE  RICHARDSON. 


Notes  on  Behavior  of  Rats  with  Turned  A pparatus. 


TRIAL. 

1/7/08 

Cage  and  box  in  first  position,  (A);  door  of  problem 
box  on  south. 

Rat  I. 

1 

2 

3 

4 

Direct  to  door.  Time:  .03  min. 

(Cage  in  changed  position,  door  on  east,  90°  to  right) 
Went  to  old  position  of  door,  ‘nosed’  the  wire  on 
south  of  box,  became  confused,  went  to  west,  back 
to  south,  strayed  around  close  to  side  of  the  box; 
vibrissae  touched  latch  in  passing;  rat  stopped,  lifted 
latch,  but  did  not  enter  at  once.  Time;  .29  min. 

Struck  door  in  hurrying  past  corner,  hesitated,  turned 
back,  started  on,  turned  back  again  and  lifted  latch. 
Time:  .06  min. 

Repeated  movements  of  trial  3.  Time:  .06  min. 

Rat  II. 

1 

2 

3 

4 

(Cage  in  original  position,  (A).  Time:  .03  min. 

(Cage  in  changed  position  (B).  Confused  by  entrance, 
went  to  west,  paused  at  south,  came  back  to  door, 
(found  it  by  snout.?),  hesitated,  then  lifted  latch  and 
entered.  Time:  .31  min. 

Confused,  went  past  door,  hesitated,  went  to  old  posi¬ 
tion,  came  back,  found  door  apparently  by  touch, 
opened  it,  but  did  not  enter  at  once.  Time:  .15  min. 

Badly  confused;  wanders  all  about  cage.  Went  to  door 
in  new  position,  ‘nosed’  it,  but  went  away.  Entered 
finally,  more  confused  than  ever.  Time:  .69  min. 

Rat  III. 

1 

2 

3 

4 

(Cage  in  original  position,  (A).  Went  so  fast  he  ran  past 
door,  and  then  came  back.  Time:  .04  min. 

(Cage  in  changed  position  {B).  Turned  around  and 
seemed  utterly  at  a  loss;  went  past  door  to  south, 
“nosed,”  climbed  on  box  and  down  on  south,  tried  to 
raise  wires  again;  strayed  about  until  he  came  upon 
door,  sniffed  at  it  carefully  and  leisurely,  went  on, 
came  back,  evidently  received  stronger  touch  stimu¬ 
lation,  then  raised  latch  in  his  usual  way.  Time: 
.49  min. 

Passed  door,  turned  back,  hesitated,  moving  head  from 
side  to  side,  lifted  latch  and  entered.  Time:  .09  min. 

Directly  to  south,  then  back  to  east.  Time;  .09  min. 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


55 


The  notes  call  attention  to  three  characteristics  of  the  ani¬ 
mals’  behavior  under  the  new  conditions:  (i)  The  immediate 
excursion  to  the  south  side  of  the  box;  (2)  confusion  at  failing 
to  find  the  door;  (3)  nosing  about  to  discover  the  door,  and  (4) 
the  discovery  of  it  made  apparently  in  these  cases  at  least,  on 
the  data  afforded  by  either  the  contact  of  the  vibrissae,  or  of 
the  snout  with  the  latch  or  with  the  door.  The  door  was  not 
held  firmly  in  place  by  the  latch,  but  wavered  slightly  when 
an  animal  exerted  pressure  upon  it  with  its  snout  or  with  its 
claws.  .This  yielding  of  the  door  apparently  often  stimulates 
a  general  motor  overflow  which  results  in  movements  of  vig¬ 
orously  biting  and  clawing  at  the  door  even  before  the  animal 
associates  the  door  with  the  process  of  procuring  food.  It 
is  quite  probable  that  as  the  rat  searches  for  the  entrance  to 
the  box,  the  yielding  of  the  door  or  the  mobility  of  the  latch 
is  the  stimulus  which  releases  the  movements  that  raise  the 
latch. 

There  was  no  indication  that  any  of  the  rats  located  the 
door  by  means  of  vision,  for  each  rat  passed  the  door  while 
‘searching’  for  it  without  reacting  to  it.  Yet  when  the  door 
was  touched  there  followed  the  examination  of  the  latch,  and 
the  performance  of  the  requisite  movements  to  open  the  door. 

The  next  day  after  these  tests  and  the  second  day  following, 
these  experiments  were  continued,  with  the  same  general 
results.  When  the  door  of  the  control  cage  was  turned  to  the 
north,  the  rats  went  first  to  the  south,  then  to  the  east,  finally 
locating  the  door  as  before, — probably  with  the  snout.  But 
each  rat  went  frst  to  the  south,  where  the  door  had  been  two 
days  before.  The  old  pathway  involved  a  turn  first  to  the  left, 
then  to  the  right,  then  to  the  right  again.  In  the  new  position 
each  rat  lengthened  his  path  and,  after  making  the  previous 
series  of  turns  as  before,  added  another  turn  to  the  right,  arriv¬ 
ing  at  the  absolute  spot  to  which  his  shorter  path  had  hitherto 
brought  him. 

A  blind  black-and  white  rat  was  tested  in  the  same  manner, 
with  the  cage  and  box  in  the  two  positions.  He  exhibited  the 
same  characteristics  as  the  normal  rats,  except  that  in  his 
confusion  he  went  over  the  food  box,  a  habit  that  he  had  ac- 


56 


FLORENCE  RICHARDSON. 


quired  in  learning  the  problem.  The  habit  had  almost  dis¬ 
appeared,  but  when  his  first  attempts  were  unsuccessful,  he 
reverted  to  his  early  random  movements.  His  time-records  with 
the  box  in  the  changed  position  suffered  no  greater  increase 
than  those  of  the  normal  rats  under  the  same  conditions. 

These  tests,  like  those  involving  the  changed  position  of 
the  plane,  were  not  sufficiently  well  controlled  to  justify  carry¬ 
ing  them  further.  The  animals  bad  learned  the  problem  with 
the  source  of  light  to  the  west.  When  the  apparatus  was 
changed,  the  brightness  values  of  different  parts  of  the  field 
were  also  changed,  whereas  they  should  have  remained  con¬ 
stant.  In  addition  to  this,  the  control  cage  was  not  large 
enough  to  permit  the  rat  to  go  to  the  entrance  to  the  door  of 
the  problem  box  without  brushing  the  corner  of  the  box.  In 
this  way  one  rat  accidently  discovered  the  latch  in  passing.  To 
control  the  conditions  properly  in  such  an  experiment,  a  larger 
control  cage  covered  with  canvas,  and  lighted  from  within, 
would  be  necessary. 

The  above  test  seems  to  indicate  the  value  of  touch  in  locat¬ 
ing  the  latch.  The  normal  rats,  like  the  blind  rat,  seemed  to 
discover  the  latch  by  contact.  The  functioning  of  anything 
like  discriminative  vision  could  not  be  detected  in  the  behavior 
of  any  animal  submitted  to  these  tests.  If  such  data  had  been 
made  use  of,  the  fact  should  have  been  apparent  in  the  method 
of  discovering  the  door.  A  rat  when  ‘searching’  for  the  door 
often  passed  it,  and  seemed  oblivious  to  its  location  although  it 
was  not  more  than  three  inches  distant. 

The  behavior  of  the  animals  in  this  experiment  justifies  the 
discussion  of  the  behavior  of  rats  in  tests  in  which  the  position 
of  the  plane  was  changed  (Problem  II,  p.  38).  The  contention 
was  there  advanced  that  there  was  no  evidence  of  the  percep¬ 
tion  of  the  plane  by  the  rat:  That  the  plane  was  not  isolated 
from  the  rest  of  the  environment.  In  the  test  with  Problem 
III,  there  is  no  evidence  that  the  latch  or  the  door  was  singled 
out  and  reacted  to  as  an  object. 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


57 


h* 


58 


FLORENCE  RICHARDSON. 


Summary. 

a.  Average  Time-records  for  the  Total  Series  of  Trials. 

The  following  table  shows  the  average  of  the  total  time 
consumed  for  the  different  groups  of  rats  for  a  series  of  15 
trials.  It  has  been  necessary  to  make  a  comparison  on  the 
basis  of  this  number  of  trials  since  the  normal  white  rats, 
which  were  first  tested  had  reached  a  stage  of  proficiency  in 
the  solution  at  which  their  reactions  were  constant  and  habitual. 
The  later  records  of  the  other  groups  are  given  in  the  following 
section. 


TABLE  SHOWING  GROUP  AVERAGE  OF  THE  TOTAL  TIME  (15  TRIALs)  CONSUMED 
BY  NORMAL  AND  BY  DEFECTIVE  ANIMALS  IN  LEARNING  PROBLEM  III. 


min. 


mtn. 


Normal  White . 50  Blind .  1.81 

Black-and-White . 18 


TABLE  SHOWING  INDIVIDUAL  AVERAGES  OF  TOTAL  TIME  CONSUMED  IN  FIFTEEN 

TRIALS. 


Normal  White. 

Black-an 

d~  White. 

Blind. 

min. 

min. 

min. 

Male 

I . 

•36 

Female  III. 

. 24 

Male  IV . 

•63 

Male 

II . 

.69 

Female  IV. 

. 12 

Female  IV . 

2.95 

Male 

Ill . 

■33 

Female  V . 

1.85 

Male  IV... 
Female  II. 
Female  III. 


24 

61 

79 


The  great  difference  in  the  group  averages  of  the  normal 
white  and  the  black-and-white  rat  is  due  to  the  very  long  time- 
record  of  the  white  rats  at  the  first  trial.  The  average  of  the 
blind  animals  is  high  although  the  average  of  Blind  Male  IV 
is  less  than  that  of  Normal  Male  II  and  that  of  Normal  Female 
III.  Unfortunately  the  fact  that  there  remained  buttwo  black- 
and-white  animals  renders  this  group  practically  unavailable 
for  purposes  of  comparison. 


A  STUDT  OF  SENSORr  CONTROL  IN  THE  RAT. 


59 


b.  Average  Time-records  by  Groups  of  Five  Trials. 

Normal  White. 


Individuals. 


TRIALS. 

MALE  I. 

MALE  II. 

MALE  III. 

MALE  IV. 

FEMALE 

II. 

FEMALE 

III. 

GROUP. 

rntn. 

mtn. 

min. 

mtn. 

min. 

min. 

min. 

I-  5 

•97 

1-95 

•83 

.60 

1 .64 

2 . 19 

1.36 

6-10 

.08 

.08 

.09 

.  10 

.  12 

■  14 

.  10 

11-15 

•03 

■05 

.07 

.04 

.06 

.05 

•05 

Black- and- White  Rats. 


FEMALE  HI. 

FEMALE  IV. 

GROUP. 

min. 

min. 

min. 

I-  5 

.60 

.22 

•41 

6-10 

.08 

.06 

.07 

11-15 

.06 

.08 

.07 

16-20 

•07 

.05 

.06 

21-25 

.05 

.05 

.05 

Blind  Rats. 


TRIALS. 

MALE  IV 

FEMALE  IV. 

FEMALE  V. 

AVERAGE. 

mtn. 

min. 

min. 

mtn. 

I-  5 

1.36 

5-49 

b 

00 

3  64 

6-to 

.26 

2.76 

1 . 10 

1-37 

11-15 

.26 

.60 

•42 

•43 

16-20 

.40 

.18 

.24 

.27 

21-25 

.22 

.18 

•36 

•25 

26-30 

.21 

.20 

.22 

.21 

31-36 

.26 

.20 

1.42 

.29 

36-40 

•31 

•13 

.46 

•30 

There  is  not  much  to  be  added  in  comment  on  these  tables. 
They  point  out  the  fact  that  there  is  little  or  no  difference  in 
the  time-records  of  the  white  and  the  black-and-white  rats,  and 
a  very  considerable  difference  in  those  of  the  normal  and  the 
blind  rats.  No  blind  rat  made  an  average  for  ten  trials  in 
later  trials  so  low  as  the  highest  group  average  for  the  normal 
rats  in  such  trials. 


6o 


FLORENCE  RICHARDSON. 


Probably  only  the  blind  rats  were  given  a  sufficient  number 
of  trials  in  this  problem  to  render  apparent  a  tendency  towards 
the  dissolution  of  the  association  that  has  been  commented  on 
in  similar  records  for  animals  on  Problems  I  and  II.  Three 
of  four  of  the  blind  rats  raise  their  averages  near  the  end  of 
the  series. 

c.  Comparison  of  the  Curves  of  the  Different  Groups. 

The  curve  representing  the  average  of  the  normal  white 
rats  is,  in  this  problem,  more  uniform  than  in  either  of  the 
preceding  problems.  While  the  first  trial  is  high,  the  curve 
drops  very  rapidly,  reaching  and  maintaining  its  low  level 
on  and  after  the  sixth  trial. 

The  curve  of  the  black-and-white  group  is  much  lower  at 
the  first  trial,  and  does  not  make  such  a  rapid  descent,  though 
at  the  fifth,  sixth,  seventh,  and  eighth  trials  it  is  lower  than 
that  of  the  normal  white  rat.  At  the  twelfth,  thirteenth,  four¬ 
teenth,  and  fifteenth  trials  they  run  no  more  than  .01  min. 
apart.  The  third  curve,  that  of  the  blind  animals,  is  of  a 
different  contour,  as  it  drops  much  more  gradually.  At  no 
point  in  the  series  of  5  trials,  does  it  reach  a  level  near  that  of 
either  of  the  groups  of  normal  rats.  The  curve  is  also  quite 
irregular.^ 

D.  DISCUSSION  OF  CURVES  SHOWING  AVERAGE  TIME-RECORDS 
OF  NORMAL  AND  OF  DEFECTIVE  RATS  IN  LEARNING  THE  MAZE. 

On  account  of  the  necessity  of  plotting  the  curves  shown  in 
this  paper,  on  a  much  larger  scale  than  that  employed  in 
Watson’s  monograph,  the  difference  between  the  blind  and 
the  normal  rats  seems  much  magnified.  The  time-records  for 
the  later  trials  on  the  maze  rarely  run  below  .25  min.,  while 
those  on  Problem  I  of  this  work  go  as  low  as  .02  min.  A 
curve  constructed  from  data  given  by  Watson’s  records^  of 
the  normal,  blind,  and  anosmic  animals  on  the  maze,  plotted 

*  The  comparison  of  these  curves  should  be  supplemented  by  an  examination 
of  the  curves  obtained  from  the  records  of  untrained  animals  on  this  problem. 
These  curves  are  given  on  Plates  VI  and  VII. 

^Watson,  ibid.,  pp,ig,  59  and  62. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


6l 


on  the  scale  here  employed,  is  shown  in  Plate  IV.  Had  the 
curves  for  the  records  of  the  rats  on  Problem  I  been  plotted 
on  the  scale  employed  by  Watson,  the  differences  in  the  curves 
would  have  practically  disappeared. 

The  curve  showing  the  records  of  the  normal  rats  is  made 
up  from  the  averages  of  four  normal  white  males  of  one  litter 
about  one  year  old.  That  of  the  blind  rats  is  made  up  of  the 
averages  of  four  blind  males  thirty-four  weeks  old.  At  no  point 
do  the  time-records  of  the  normal  rats,  trial  by  trial,  go  lower 
than  that  of  the  blind.  At  only  two  points  on  the  curve  do 
they  go  as  low.  The  fact  that  they  were  younger  and  probably 
more  active  may  partly  account  for  the  lower  records  made  by 
the  blind  rats.  But  a  comparison  of  the  average  of  the  blind 
animals  with  that  of  the  nineteen,  whose  records  go  to  make 
up  the  norm,  shows  the  same  low  record  for  the  blind. 

Watson  has  formulated  the  conclusion  that  rats  can  learn 
the  maze  without  the  use  of  vision.  The  present  writer  has 
the  temerity  to  suggest  in  the  face  of  some  later  results  that 
vision  not  only  adds  nothing  of  advantage,  but  may  quite 
conceivably  be  detrimental  to  the  rapidity  of  the  learning  of 
the  maze.  It  has  been  shown  that  the  maze  may  be  learned 
almost  absolutely  in  terms  of  kinaesthetic  and  organic  impulses. 
Since  these  impulses  alone  are  sufficient,  visual  impulses  might 
be  conceived  of  as  adding  a  distraction. 

The  curve  from  the  records  of  the  anosmic  rats  is  shown 
upon  the  same  plate.  The  curve  from  this  group  runs  slightly 
below  that  of  the  normal  but  above  that  of  the  blind.  Here, 
as  in  the  case  of  the  blind  rats,  it  is  possible  that  olfactory 
impressions  may  be  a  stimulus  to  movements  which  in  this 
problem  are  detrimental  to  the  learning  process. 

E.  GENERAL  CONCLUSION  BASED  UPON  RESULTS  OF  ABOVE  TESTS. 

The  experiment,  the  results  of  which  will  be  reported  next, 
is  one  that  does  not  require  the  formation  of  an  association 
such  as  has  been  required  in  the  three  foregoing  experiments. 
Its  results,  therefore,  will  not  be  considered  in  connection  with 
those  just  presented.  A  summary  of  facts  will  be  attempted 
here  together  with  a  discussion  of  their  theoretical  import. 


MjnuJei 


62 


FLORENCE  RICHARDSON. 


rruj,  os 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


63 


The  aim  of  the  investigation  has  been  to  determine  upon 
what  sensory  impulses  the  rat  mainly  depends  in  forming  the 
var  ous  associations  required  in  these  problems.  The  func¬ 
tion  of  the  different  sense  processes  will  be  taken  up  in  detail. 

I  Vision.^ 

a.  Differences  in  Functional  Value  of  Vision  in  Rats  Pos¬ 
sessing  Pigmented  and  those  Possessing  Albino  Eyes. 

The  evidence  of  greater  importance  of  vision  in  rats  pos¬ 
sessing  pigmented  eyes  is,  upon  the  whole,  equivocal.  In 
Problem  I  (see  p.  13)  the  black-and-white  animals  made  phe¬ 
nomenally  low  records;  not  only  is  the  average  absolute  time 
of  the  group  much  lower  than  that  of  any  other  group  upon 
this  problem,  but  the  highest  individual  record  of  the  black- 
and-white  groups,  is  considerably  lower  than  the  lowest  aver¬ 
age  record  of  any  normal  rat.  The  curve  representing  the 
average  of  the  black-and-white  animals  is  more  regular,  and 
the  individual  variability  is  less,  in  this  group  than  in  any  other. 
These  facts  if  taken  alone,  would  seem  to  indicate  that  the  black- 
and-white  rats  were  at  an  advantage  in  Problem  I.  In  the 
same  problem,  however,  the  two  white  rats,  which  had  had 
previous  experience  in  other  problems,  made  still  lower  records, 
(p.  103). 

In  Problem  II  there  was  little  difference  in  the  average 

^  The  term  vision  up  to  this  point  has  been  used  in  the  most  general  way.  At 
this  juncture  it  seems  necessary  to  qualify  its  significance  and  to  indicate  the 
different  ways  in  which  impulses  from  the  eye  may  be  rendered  serviceable. 

1 .  Possibly  the  most  primitive  function  of  such  impulses  is  that  of  heighten¬ 
ing  the  general  tonicity  of  the  motor  area.  This  hypothetical  tonic  effect  of 
light  impulses  is  referred  to  more  extensively  later. 

2.  White  light  vision  implies  that  an  animal’s  reactions  may  be  modified  in 
accordance  with  the  brightness  of  visual  stimuli. 

3.  The  term  color-vision  implies  that  the  animal  can  react  in  a  selective 
way  to  light  stimuli  of  different  wave  lengths. 

4.  Form-and-size- vision  would  be  said  to  be  present  if  the  animal  were  able 
to  discriminate  the  form  and  size  of  the  visual  stimulus  to  which  he  reacts. 

5.  A  further  possibility  is  depth  discrimination,  which  in  the  rat  may  or  may 
not  involve  retinal  factors.  One  would  infer  the  presence  of  this  form  if  the 
animal  were  able  to  react  accurately  to  stimuli  placed  at  varying  distance  inter¬ 
vals  in  the  line  of  vision,  provided  that  one  were  certain  that  no  other  form  of 
sensory  impulse  were  operative. 


64 


FLORENCE  RICHARDSON. 


absolute  time-records  of  these  two  groups  (see  p.  42),  although 
five  normal  white  individuals  made  average  absolute  time- 
records  lower  than  the  lowest  individual  of  the  black-and-white 
group.  The  time-records  of  the  normal  white  group — as 
shown  in  series  of  ten  trials  each  (p.  44) — are  uniformly 
lower  ten  by  ten — than  the  corresponding  records  of  the  black- 
and-white  group,  while  the  lowest  individual  records  in  such 
a  series  were  made  by  those  having  albino  eyes.  The  time- 
record  of  the  white  rats  was  lower  for  the  first  ten  trials,  and 
the  difference  between  that  of  the  first  and  second  ten  was  in 
their  favor.  The  curve  is  lower  for  the  white  rats  to  the  25th 
trial,  and  from  that  point  there  is  no  advantage  accruing  to 
either  group. 

These  facts  indicate  that  in  this  problem  the  rats  with  albino 
eyes  made  slightly  better  records  than  those  with  pigmented  eyes. 

In  Problem  III  the  black-and-white  rats  made  a  much 
better  average  absolute  time-record,  and  their  individual  records 
were  lower.  (See  p.  32.)  The  tables  giving  the  average  abso¬ 
lute  time-records  in  groups  of  5,  show  a  much  lower  average 
for  the  black-and-white  rats  in  the  first  and  second  series  of 
five  trials  each,  but  in  the  third  series,  the  white  rats  made  not 
only  a  lower  average  record,  but  no  black-and-white  individual 
made  so  low  a  record  as  that  of  certain  individual  white  rats. 

In  the  results  of  experimentation  reported  later  (p.  103)  a 
comparison  may  be  made  between  the  time-records  of  four 
untrained  white  rats,  and  four  untrained  black-and-white  rats 
on  Problem  III.  The  untrained  black-and-white  animals 
made  a  lower  record  for  the  first  series  of  five,  a  higher  rate 
for  the  second  and  third  series,  a  lower  for  the  fourth  and  fifth, 
and  a  higher  for  the  sixth. ^  As  has  been  shown  in  Part  II, 


^  Untrained  Untrained 

white  rats,  black-and-white  rats. 

1-5 . . II.  12  min.  5.04  min. 

6-10 . 60  1 . 16 

11-15 .  .21  .31 

16-20 .  .18  .14 

21-25 . 10  .08 

26-30 .  .06  .08 

31-35 .  -05 

36-40 .  .06 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


65 


rats  which  have  had  experimental  experience  are  much  more 
apt  in  learning  a  new  problem,  presumably,  largely  because  of 
less  timidity  during  the  experimentation.  The  black-and- 
white  rats  which  made  low  records  in  Problem  I  were  unusually 
tame  at  the  beginning  of  the  work,  which  probably  accounts 
for  their  more  rapid  success.  They  were  noticeably  superior 
on  Problems  II  and  III. 

It  must  be  admitted  after  the  consideration  of  the  above 
data,  that  the  evidence  regarding  the  comparative  functional 
value  of  vision  in  rats  possessing  pigmented  and  those  which 
have  albino  eyes  is  not  decisive. 

b.  Effect  of  Loss  of  Vision. 

The  following  discussion  must,  in  the  nature  of  the  case, 
deal  with  the  effect  of  the  loss  of  vision  rather  than  with  its 
explicit  function  when  present  in  the  normal  animal.  The 
entire  series,  as  remarked  above,  afforded  no  opportunity  for 
determining  the  exclusive  function  of  vision.  The  change  in 
conditions  in  the  tests  on  Problems  II  and  III  illustrate  this 
point:  the  animals  did  not  seem  to  rely  upon  visual,  but  rather 
upon  tactual  and  kinaesthetic  stimuli,  yet  the  blind  rats  were 
at  a  disadvantage  as  compared  with  the  normal  animals. 

The  least  apparent  difference  between  the  blind  and  the  nor¬ 
mal  white  rats  is  in  Problem  I,  The  records  of  the  normal  rats, 
as  a  group,  are  better;  the  absolute  average  time  for  the  white 
group  is  lower  (see  p.  21),  although  the  difference  between 
these  averages  of  the  two  groups  is  less  than  the  individual 
variations  among  the  normal  rats.  The  average  of  the  abso¬ 
lute  time  for  the  poorest  two  normal  males  and  two  females 
(Males  II,  III  and  Females  I  and  V,  averaging  .41  min.) 
compared  with  that  of  the  best  two  blind  males  and  two  females 
(Males  III,  IV  and  Females  III  and  V,  averaging  .27  min.) 
proves  this  statement  conclusively.  In  fact,  if  the  poorest  two 
records  of  the  nine  blind  rats  be  rejected,  the  average  for  the 
remaining  seven  animals  is  .33  min.,  which  compares  most 
favorably  with  the  group  average,  .34  min.,  of  the  normal  rats.‘ 

'  The  extremely  high  records  of  the  two  blind  animals,  Male  I  and  Female  I, 
are  responsible  for  the  higher  group  average  of  the  blind  rats. 


66 


FLORENCE  RICHARDSON. 


As  regards  the  rate  of  learning,  the  normal  rats  were  superior 
(see  p.  2i).  The  first  two  successes  of  the  blind  rats  were 
accomplished  more  quickly  (see  Plate  I)  than  those  of  the 
normal,  though  from  the  fifth  trial  to  the  end  of  the  series 
the  curves  representing  the  normal  rats  is,  for  the  greater 
portion  of  its  length,  below  that  of  the  blind  animals. 

In  Problem  II  it  may  be  questioned  whether  the  blind  rats 
formed  the  necessary  association  for  the  solution.  But  two 
animals.  Females  IV  and  V  (see  p.  42),  so  reduced  their  time- 
records  that  their  individual  curves  approach  the  contour  of  a 
learning  curve.  The  records,  averaged  in  groups  of  ten, 
show  that  there  is  not  a  sufficient  reduction  in  the  time-records 
to  warrant — on  the  basis  of  time  consumed — the  assumption 
that  these  rats  were  successful  in  this  problem.  The  behavior 
of  several  of  the  animals  at  the  end  of  the  series  warranted  the 
statement  that  no  definite  path  was  chosen  The  greater  varia¬ 
bility  of  the  group  renders  its  average  absolute  time  useless 
as  a  basis  of  comparison.^ 

A  comparison  of  the  graphs  showing  the  average  time-records 
of  the  various  groups  (see  Plate  II)  suggests  the  doubtful 
justification  of  considering  the  curve  of  the  blind  animals  as 
a  learning  curve  at  all.  It  must  be  recalled  here,  however, 
that  two  blind  rats  did  arrive  at  the  solution,  though  somewhat 
more  slowly  than  any  normal  rat. 

In  Problem  III,  likewise,  there  is  a  very  considerable  differ¬ 
ence  in  the  records  of  the  two  groups.  The  blind  rats  learned 
to  solve  the  problem,  though  the  absolute  time  is  higher  through¬ 
out  the  series,  and  the  rate  of  learning  much  slower  (see  p.  59). 
The  individual  variations  as  to  time-records  is  not  nearly  so 
evident  here  as  among  these  individuals  on  Problem  II. 

The  differences  in  the  results  obtained  in  tests  with  blind 
animals,  and  with  those  which  possess  vision,  vary  with  the 
nature  of  the  experiment  to  which  the  two  groups  are  sub¬ 
jected.  Watson  found  that  vision  could  be  dispensed  with  in 
the  learning  of  the  maze  without  perceptible  loss  to  the  process. 
In  Problem  I  of  this  series  there  was  but  little  advantage 

'  Compare  the  average  record  of  Blind  Female  II  for  the  first  ten  trials  with 
that  of  any  other  normal  or  defective  rat. 


J  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


67 


accruing  to  the  normal  animals;  in  Problem  III  there  was 
considerable,  and  in  Problem  II  the  blind  animals  were  at  a 
decided  disadvantage.  In  the  face  of  these  facts  it  seems 
possible  that  the  loss  of  vision  is  disadvantageous  to  the  solution 
of  these  problems  in  proportion  as  the  problems  demand 
movement  which,  to  be  effective,  must  be  definitely  controlled 
as  to  the  exact  locality  in  which  it  is  to  be  put  forth.  In  the 
maze,  the  activity  of  the  animal  is  definitely  confined  by  the 
maze  itself;  namely,  narrow  alleys  which  the  rat  must  traverse. 
Problem  I  approximates  the  labyrinth  type  in  that  the  animal, 
during  the  solution  of  the  problem,  is  somewhat  restricted  in 
its  movements  by  the  nature  of  the  apparatus.  Problem  III 
demands  movements  performed  within  a  definite  area,  move¬ 
ments  unrestricted  save  by  the  motor  tendencies  of  the  animal. 
Problem  II  demands  a  similarly  specialized  movement  with 
the  added  complication  that  the  area  in  which  the  movement 
must  be  performed  is  at  a  distance  from  the  food  stimulus. 
Assuming  that  the  above  problems  represent,  in  the  order  I, 
III  and  II  a  series  of  increasing  specializations  of  adaptive 
reactions,  it  would  seem  that  the  loss  of  vision  becomes  more 
disadvantageous  throughout  the  series. 

The  above  tests  are  not  of  such  a  character  as  to  afford 
unequivocal  evidence  concerning  the  possible  function  of 
vision. 

The  eye  as  previously  stated  affords  impulses  to  the  motor 
center  which  are  presumably  tonic  in  character.  The  motor 
impulses  which  are  to  result  in  general  bodily  movement  are 
always  conditioned  by  the  sum  of  tendencies  operative  in  the 
motor  area.  If  the  tonic  condition  of  this  area  is  low,  as  might 
be  the  case  in  blind  animals,  it  might  well  happen  that  the 
requisite  association  would  be  slow  in  forming.  It  is  possible 
in  this  way  to  account  for  the  fact  that  although  in  their  behavior 
these  animals  gave  no  evidence  as  to  the  function  of  vision 
the  rats  that  through  blindness  may  have  had  an  insufficient 
energy  surplus  of  the  kind  called  for  in  these  coordinations 
were  slow  in  learning  or  failed  to  learn  in  so  far  as  the  problems 
demanded  well  concatenated  activities. 


68 


FLORENCE  RICHARDSON. 


2.  Olfaction. 

The  group  of  anosmic  rats  made  a  higher  average  absolute 
time-record  for  Problem  I  (see  p.  21),  and  the  rate  of  learning 
was  comparatively  poor  for  the  group  as  a  whole.  Two  indi¬ 
viduals,  Males  III  and  IV  made  records  that  were  lower — in 
series  of  ten  trials  each — than  the  average  of  the  normal 
group. ‘  The  average  time  for  the  first  ten  trials  is  particularly 
low  for  Males  II  and  III.^  The  individual  variation  is  high. 

On  Problem  II  the  time-records  of  the  one  anosmic  rat  are 
valueless  as  a  basis  of  comparison.  He  learned  the  problem, 
but  did  not  solve  it  as  the  other  animals  had  done  (see  p.  34). 

Problem  III  was  also  learned  in  an  eccentric  fashion,  which 
vitiated  the  time-records,  although  the  association  was  well- 
formed  and  at  the  rate  of  the  normal  rat  (see  p.  52). 

In  the  learning  of  the  above  problem  it  is  not  necessary  for 
the  rat  to  establish  and  follow  a  pathway  on  the  basis  of 
olfactory  impressions.  Such  impressions  may  accelerate  or  re¬ 
tard  the  learning  process;  accelerate  when  the  odor  is  a  part  of 
the  stimulus  connected  with  the  problem  box,  e.  g.,  when  the 
stimulus  releases  movements  which  may  result  in  the  successful 
manipulation  of  the  apparatus,  such  as  clawing  or  biting  at  a 
latch;  otherwise  disadvantageous,  resulting  in  the  dispersal  of 
‘attention,’  as  when  the  rat  spends  time  in  smelling  the  control 
cage;  or, as  in  Problem  II,  in  sniffing  at  the  food,  when  his  move¬ 
ments  to  be  successful,  must  be  performed  elsewhere.  This  is 
the  probable  explanation  of  the  fact  that  the  time-records  of 
the  anosmic  rats  are  frequently  lower  than  the  corresponding 
records  of  normal  animals. 

J.  Touch. 

The  impulses  furnished  by  the  sense  of  touch  seem  to  play 
an  important  part  in  the  adaptation  of  the  animal  to  these  sev- 

‘  Eliminating  the  record  of  the  first  ten  trials  of  Male  III,  which  was  high 
because  of  a  very  long  time  consumed  in  his  first  success,  the  average  of  the 
group  for  the  trials  from  i-io,  .84  min.,  is  much  lower  than  that  of  the  normal 
rats. 

*  Compare  these  records  with  that  of  the  blind  anosmic  rat,  given  on  p.  106. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


69 


eral  experimental  situations.  A  very  great  difficulty  arises 
when  an  attempt  is  made  to  separate  the  functions  of  the 
tactual  from  that  of  the  kinaesthetic  and  organic.  The  tactual 
impulses  alone,  or  in  the  complex,  are  the  stimuli  to  the  digging 
movements  in  Problem  I,  and  in  part  to  the  movements  of 
pressing  down  the  plane  in  Problem  II.  In  Problem  III, 
certain  familiar  tactual  impressions  are  evidently  the  stimuli 
to  the  discovery  of  the  latch  after  the  rat  has  arrived  at  the 
locality  of  the  door.  Contact  seems  also  to  be  the  cue  to  move¬ 
ments  which  result  in  raising  of  the  latch,  during  both  the 
learning  process  and  the  period  in  which  the  movements  are 
habitual. 

Kincesthetic  and  Allied  Impressions. 

The  role  of  kinaesthetic  impulses  in  the  early  processes  of 
learning  probably  varies  in  inverse  proportion  to  the  degree  in 
which  the  movements  must  be  adapted  to  a  definite  locality. 
Later  in  the  process,  as  the  movement  becomes  more  or  less 
automatic,  the  kinaesthetic  and  allied  impulses  seem  to  assume 
first  importance  as  the  means  of  control.  In  the  maze  such 
sensory  impressions  are  sufficient.  In  Problem  I  no  others  were 
indispensable  to  a  rapid  establishment  of  the  requisite  associa¬ 
tions.  In  Problem  III,  it  was  evident  that  vision  could  be 
profitably  dispensed  with  in  proportion  as  the  reactions  became 
automatic.  In  Problem  II  these  impressions  resulting  from 
muscular  activity  were  not  only  essential  in  the  following  of 
the  pathway,  but  seemed  also  to  be  of  service  in  giving  the 
cue  for  the  excursion  to  the  door  of  the  food  box  after  the 
plane  had  been  successfully  lowered. 

F.  PROBLEM  IV. 

I.  Description  of  Apparatus  and  of  Method  of  Teaching  Rats 

to  ^ump. 

The  three  foregoing  problems  have  been  solved — though 
with  varying  degrees  of  success  by  the  blind  rats — by  means 
of  an  evident  reliance  mainly  upon  kinaesthetic  and  tactual 
stimuli.  The  necessity  remained  to  devise  a  problem  in  which 


70 


FLORENCE  RICHARDSON. 


at  first  sight  it  would  seem  that  vision  must  be  the  only,  or  at 
least  the  esssential,  means  of  control. 

Dr.  Carr,  when  working  with  rats  on  the  maze,  used  one 
rat  which  jumped  from  his  hand  to  the  table,  although  the 
next  day  the  rat  jumped  in  the  direction  of  the  maze  but  struck 
the  floor.  Two  black-and-white  rats  which  worked  upon  Prob¬ 
lem  I,  in  their  anxiety  to  get  food,  acquired  the  habit  of  jump¬ 
ing  from  the  experimenter’s  hand  into  the  open  door  of  the 
cage,  a  distance  often  of  six  or  eight  inches.  These  observa¬ 
tions  suggested  the  construction  of  a  piece  of  apparatus  which 
would  necessitate  jumpiiig  as  a  means  of  obtaining  food.  It 
would  seem  that  in  such  an  activity  vision  would  be  essential 
for  successful  coordination. 

It  is  conceivable,  however,  that  the  stimulus  which  leads 
the  animals  to  jump  from  one  platform  to  the  other  may  come 
through  one  or  more  of  three  pathways:  (i)  visual,  (2) 
olfactory,  (3)  tactual  and  kin?esthetic.  Factors  i  and  2  alone 
would  be  adequate  to  control  the  direction  and  distance  of 
the.  first  jump.  Factor  3  might  cause  jumping  to  occur,  but 
only  after  some  experience  of  consequence  would  it  serve  to 
control  the  distance  and  direction  of  the  leap.  Under  the  con¬ 
ditions  of  the  experiments  here  considered,  it  was  possible  to 
eliminate  contact  as  a  means  of  sensory  control  by  keeping 
the  tactual  conditions  constant  throughout  all  the  experiments. 
The  attempt  to  eliminate  the  kinaesthetic  factor  was  made  by 
varying  irregularly  the  distance  between  the  two  platforms. 
Smell  was  eliminated  by  the  use  of  anosmic  animals,  by  keeping 
the  apparatus  clean,  and  by  control  experiments  upon  the 
normal  animals  in  which  no  food  was  given  until  after  the 
jump  had  been  taken.  It  was  thought  that  the  role  of  vision, 
the  remaining  factor,  could  be  determined  by  comparing  the 
behavior  of  the  normal  animals  with  that  of  the  blind.  In 
view  of  the  fact,  however,  that  the  normal  animals  were  so 
deficient  in  the  ability  to  control  their  movements  when  the 
distance  between  the  platforms  was  altered,  the  experiments 
are  not  decisive  as  regards  determining  the  nature  of  the  role 
which  vision  plays. 

The  factors  involved  in  this  coordination  are  so  delicate 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


71 


and  so  complex  that  the  time  allotted  to  it  was  not  sufficient 
to  answer  all  the  questions  which  arose.  Indeed,  the  experi¬ 
menter  feels  that  many  of  the  questions  which  are  here  tenta¬ 
tively  answered  must  be  supported  by  a  much  larger  group 
of  facts  before  they  should  have  anything  like  scientific  assent. 


The  first  apparatus  used  in  this  experiment  consisted  of  two 
2  inch  by  2  inch  wooden  uprights  20  inches  high,  each  sur¬ 
mounted  by  a  5  inch  by  5  inch  platform  of  i  inch  board.  The 
uprights  were  attached  below  to  a  4  foot  length  of  2  inch  by 
2  inch  timber,  supported  by  wooden  legs.  One  of  the  uprights 
was  fixed,  the  other  movable.  The  distance  between  the  plat- 


72 


FLORENCE  RICHARDSON. 


forms^  might  be  varied  from  o  to  40  inches.  The  entire 
apparatus  was  painted  white. 

The  first  group  of  rats  consisted  of  four  normal  white  males. 
Their  exact  ages  were  unknown,  but  were  estimated  about 
180  days.  They  had  been  used  previously  for  three  weeks  in 
tests  upon  the  maze,  and  were  accustomed  to  being  handled. 
Since  time-records  were  not  sought  here,  but  information 
about  the  delicacy  of  functioning  of  such  visual-motor  adjust¬ 
ments  as  would  be  required  in  jumping  coordinations,  the  age 
and  the  training  of  the  rats  were  not  matters  of  concern. 

These  animals  had  learned  to  jump  from  the  experimenter’s 
hand  to  the  open  door  of  the  cage,  and  had  accomplished  these 
feats  at  varying  distances  up  to  12  inches.  When  they  were 
put  to  work  upon  the  apparatus,  they  had  acquired  the 
coordinations  for  short  distances.  These  coordinations  are  not 
common  to  rats  held  in  captivity.  They  do  make  short  leaps 
in  springing  to  and  from  the  wire  sides  of  their  cages,  but  any 
such  long  jumps  as  they  had  to  accomplish  in  these  tests  are 
entirely  foreign  to  their  usual  habits.  In  the  majority  of  cases 
the  difficulty  and  slowness  of  the  training  was  distressing  to 
the  experimenter,  though  in  several  instances  the  ease  with 
which  the  jumping  coordinations  were  acquired  was  surprising. 

Most  of  the  animals  were  emotionally  disturbed  by  the  con¬ 
ditions  of  the  experiments;  in  three  cases  a  fall  so  frightened 
the  animals  that  they  refused  for  a  time  to  react  in  later  tests. 

The  method  of  teaching  the  rats  to  jump  was  ordinarily 
laborious.  The  apparatus  was  placed  in  the  middle  of  the 
floor  in  such  a  position  that  the  rats  were  forced  to  jump 
toward  the  east.  The  platforms  were  placed  at  a  distance  of 
four  inches  apart.  The  rats  were  coaxed  across  with  a  morsel 
of  food.  Platform  II  was  within  reach  of  the  animal’s  nose 
and  the  step  across  was  usually  taken  without  hesitation. 
After  each  successful  effort  the  animal  was  allowed  to  eat  a 
trifling  amount  of  food.  When  the  rats  had  become  accus¬ 
tomed  to  stepping  across,  the  distance  between  the  platforms 
was  gradually  increased  one  inch  at  a  time.  Up  to  a  certain 

*  The  platform  upon  which  the  food  was  placed  and  to  which  the  rat  jumps 
will  be  designated  as  Platform  II ;  the  one  from  which  it  jumps  as  Platform  I. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


73 


distance  the  rat  was  able  to  step  across  with  little  difficulty, 
and  contact  of  the  snout  or  vibrissae  with  Platform  II  seemed 
to  be  the  essential  stimulus  in  the  majority  of  cases. 

The  difficulties  began  when  the  distance  was  increased  until 
Platform  II  was  out  of  the  reach  of  the  rat’s  snout  or  vibrissae. 
Here  a  double  complication  arose:  (l)  The  old  contact  stim¬ 
ulus  was  lacking;  and  (2)  there  was  the  necessity  for  making 
a  springing  movement,  in  which  at  one  instant,  all  four  feet 
are  without  support.  Several  rats  had  no  difficulty  at  this 
point;  some  had  great  difficulty;  but  eventually  they  learned 
to  make  the  muscular  adjustment  required  for  the  leap. 
Three  defective  rats — after  many  hours  of  coaxing — utterly 
failed  to  make  the  coordination.  The  following  notes  show 
in  detail  the  typical  behavior  of  a  normal  rat  while  learning 
to  jump. 


Diary  Notes  on  Behavior  of  Normal  White  Rat  III  (Female)  in  Learning  to 

Jump. 


INCHES. 

7RIALS. 

11/30/07 

1 2/1/07 

4 

5 

Fed  on  platform.  Small,  frail,  but  active  rat. 
All  good. 

5 

5 

All  good. 

6 

5 

All  good. 

12/2/07 

5 

5 

All  good. 

6 

5 

All  good. 

7 

5 

On  first  trial  she  scrambled  slightly;' othertrials 

8 

5 

good. 

First  trial,  struck  slightly  toward  north  side 

9 

5 

of  platform,second  trial,  on  south  side  of  plat¬ 
form,  other  trials  good. 

All  good. 

10 

5 

Scrambled  on  first  trial,  others  perfect. 

II 

5 

Scrambled  on  first  trial. 

12/3/07 

8 

I 

Went  clear  over  platform. 

9 

5 

Perfect. 

10 

5 

First  trial  a  slight  scramble,  others  perfect. 

II 

5 

Similar  behavior. 

*  The  phrase  ‘scrambled  slightly’  is  descriptive  of  those  trials  in  which  the 
rat  landed  w'ith  the  hind  feet  off  the  upper  surface  and  against  the  side  of  the 
platform.  The  word  ‘scrambled’  indicates  that  the  rat  landed  with  the  fore  feet, 
but  not  the  hind  feet  on  the  platform,  and  scrambled  on.  If  the  rat  could  not 
climb  on  easily,  the  result  was  noted  as  ‘short.’ 


74 


FLORENCE  RICHARDSON. 


INCHES. 

TRIALS. 

12/4/07 

9 

I 

Perfect. 

10 

5 

Perfect. 

II 

5 

Perfect. 

12 

5 

Perfect. 

13 

5 

First  and  fourth  trials  scrambled,  three  perfect. 

14 

5 

Scrambled  on  second  trial,  others  perfect. 

12/5/07 

II 

5 

Perfect. 

12 

3 

First  trial  landed  with  heels  on  edge,  but  struck 
squarely. 

14 

4 

First  and  second  trials,  scrambled  slightly. 

15 

4 

First  trial  short,  others  perfect. 

12/6/07 

10 

I 

Went  clear  over. 

12 

I 

Struck  squarely  but  with  great  force. 

14 

I 

Perfect. 

15 

I 

Perfect. 

16 

I 

Perfect. 

18 

3 

First  trial  scrambled,  others  perfect. 

20 

4 

As  above. 

22 

6 

Second  trial,  landed  south  of  platform. 

7'hird  trial,  struck  north  of  platform.  In  these 
long  jumps  she  landed  with  such  force  that 
she  was  almost  breathless  for  several  seconds 
afterward. 

12/7/07 

16 

I 

Would  have  slid  off  east  side  platform  if  experi¬ 
menter  had  not  caught  her. 

18 

I 

Same  procedure  as  above. 

20 

I 

Again  the  same. 

This  rat  was  not  tested  at  distances  greater  than  22  inches. 
Rats  I  and  II,  which  were  larger  animals,  had  learned  to  make 
longer  jumps.  Their  records  for  trials  greater  than  this  dis¬ 
tance  are  given  below. 


A  STUDT  OF  SEXSORF  CONTROL  IN  THE  RAT. 


7S 


lint  II. 


INCHES 

TRIALS. 

8/20/07 

22 

10 

First  and  sixth  trials,  a  little  short.  On  other 
trials  he  slid  across  platform  and  nearly  went 
olF. 

8/21/07 

24 

10 

hirst,  short;  third,  fourth  and  eighth  scrambled. 
(His  foot  was  sore.)  Second  trial  overshot; 
fourth,  to  north  side. 

8/21/07 

24 

10 

First, short;  second,  overshot;  third  and  fourth, 
to  north  side  of  platform;  eighth,  struck 
squarely,  but  had  too  much  momentum  and 
slid  off. 

26 

5 

First,  scrambled;  second,  slightly  long;  fifth 
short. 

28 

5 

Third,  short;  fifth,  overshot.  (Foot  was  sore, 
discontinued  tests  for  the  present.) 

Rat  III. 


8/23/07 

22 

10 

Third  and  sixth  trials,  scrambled. 

24 

10 

First,  short;  second,  scrambled;  third,  low. 

8/ 24/07 

26 

10 

Second  trial,  struck  north  side  of  platform; 
fourth,  slightly  short  and  to  south;  ninth, 
overshot. 

28 

10 

Second  trial,  slightly  long;  fourth,  scrambled; 
others  perfect. 

30 

10 

Second,  fourth  and  sixth  trials,  low;  rat  had 
begun  jumping  downwards.  Was  apparently 
not  aiming  at  platform. 

The  notes  mention  several  characteristic  features  of  the 
learning  process:  The  ‘scramble’  on  the  first  trials  for  length¬ 
ened  distances;  the  over-innervation  for  shortened  distances; 
and  the  frequent  compensations  for  errors,  as  when  the  rat 
landed  on  the  south  side  of  the  platform  on  one  trial,  it 
struck  upon  the  north  side  on  the  next  trial. ^  This  character¬ 
istic  is  referred  to  in  the  discussion  of  a  later  test. 

*  I  he  experimenter  attempted  to  devise  some  means  whereby  an  objective 
measurement  of  the  rat’s  coordination  could  be  taken.  If  the  records  could  have 
been  obtained  of  the  exact  point  at  which  the  fore  feet  first  came  in  contact  with 
the  plaform,  a  curve  could  be  plotted  showing  the  accuracy  of  the  adjustment. 
A  cloth,  marked  in  black  and  white  squares  i  cm.  in  size,  was  carefully  tacked 
over  the  top  of  Platform  II.  The  experimenter  endeavored  to  note  the  lines 


76 


FLORENCE  RICHARDSON. 


2.  "Jumping  in  Constant  Direction,  i.  e.,  A pparatus  in  East- 

fVest  Position. 

I.  Statement  of  Results, 
a.  On  Normal  White  Rats. 

The  results  of  the  tests  on  the  four  normal  white  rats  has 
been  sufficiently  discussed  in  the  description  of  the  learning 
process  in  the  foregoing  paragraphs.  Each  rat  learned  to 
jump  the  distances  up  to  and  including  22  inches.  One  had 
jumped  28  inches  with  considerable  accuracy:  one  other  had 
made  eight  perfect  coordinations  out  of  a  possible  ten  at  this 
distance,  and  seven  out  of  a  possible  ten  at  30  inches. 

Three  other  rats  learned  to  jump.  One  of  them,  a  small 
male,  learned  to  jump  a  distance  of  22  inches  in  eleven  days, 
but  was  slow  for  several  days  thereafter.  A  second,  the  best 
of  the  entire  group  at  the  first  trials,  learned  in  two  days  to 
jump  15  inches,  then  began  to  hesitate  and  finally  refused  to 
take  such  long  distances.  A  third  rat  easily  attained  a  dis¬ 
tance  of  12  inches,  after  five  days  training,  but  the  later  learning 
process  was  retarded  by  emotional  factors,  the  results  evidently 
of  a  fall  on  the  third  day  of  the  tests.  Eventually  after  five 
weeks  of  constant  training,  he  jumped  22  inches,  but  with  an 
average  of  only  50  per  cent  of  accurate  adjustments. 

b.  On  Normal  Black-and-White  Rats. 

Three  female  black-and-white  rats  were  employed  in  the 
experimentation.  Two  of  them  were  animals  which  had  been 
used  in  the  series  of  previous  problems.  Each  did  exceptionally 
well,  both  in  learning  to  jump,  and  in  the  accommodation  to 
changed  conditions  of  the  experiment.  The  third  rat  was  the 
mother  of  the  above  two,  an  extraordinarily  energetic  animal, 
and  one  without  fear.  Her  records  on  this  problem — the  only 
one  she  attempted — are  little  short  of  phenomenal.  She  was 
placed  on  Platform  I  at  a  distance  of  five  inches  from  the  food 

upon  which  the  rat  alighted,  but  the  movements  were  so  quick,  and  the  rat  so 
often  slid  along  by  reason  of  his  momentum,  that  the  attempt  was  a  failure. 
The  use  of  smoked  paper  was  likewise  out  of  the  question,  as  the  resulting 
imprint  was  only  a  large  erasure  of  the  lampblack. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


77 


platform.  She  stepped  across  at  once.  The  distance  was  in¬ 
creased  to  6  inches  and  she  did  not  hesitate.  She  jumped 
sixty  times  within  an  hour  on  her  first  day  with  but  one  error; 
these  trials  included  five  at  14  inches.  Her  complete  record 
is  given  below. 

Black-and-fVhite  Rat  Number  III. 


INCHES. 

TRIALS. 

II/I4/07 

5 

5 

First  day.  Had  never  been  placed  upon  plat¬ 
form  before.  Stepped  across  immediately. 

6 

10 

All  trials  perfect;  jumped  across  at  once. 

7 

10 

Perfect.  The  most  active  rat  we  ever  knew. 

8 

10 

Perfect. 

9 

5 

Struck  platform  squarely  every  trial  and  always 
jumped  immediately  when  she  was  returned 
to  Platform  i. 

10 

5 

All  trials  perfect. 

1 1 

5 

All  trials  perfect. 

12 

5 

All  trials  perfect. 

13 

5 

All  trials  perfect. 

14 

5 

First  trial,  struck  left  side  platform,  all  others 
squarely.  Sixty  trials  first  day! 

I I /l 5/07 

10 

I 

Went  clear  over. 

12 

I 

Struck  and  slid  off  east. 

10 

5 

First  trial,  overshot;  second,  scrambled,  others 
perfect. 

II 

5 

Good;  last  trial,  struck  and  slid  off. 

12 

5 

First  two,  a  little  short,  others  perfect. 

13 

5 

As  above.  (Not  so  active.  Muscular  soreness 
from  unusual  exertion  of  yesterday  ?) 

11/16/07 

12 

5 

Three  perfect,  two  scrambled. 

14 

5 

First  trial,  short  and  fell. 

15 

5 

First  and  second  trials,  a  little  short. 

11/17/07 

12 

5 

All  good. 

14 

5 

First  trial,  a  little  short;  second,  scrambled. 

15 

5 

Same  as  above. 

1 1/18/07 

14 

5 

Four  perfect. 

15 

5 

First  and  second  a  little  short. 

16 

5 

Good. 

17 

5 

Perfect. 

18 

5 

First  trial  did  not  strike  exactly  in  center. 

19 

5 

First  trial,  short  and  fell. 

20 

5 

A  little  short  first  trial,  others  perfect. 

21 

5 

As  above. 

22 

5 

All  perfect. 

II/I9/07 

18 

5 

■All  good. 

20 

5 

Four  trials  perfect. 

22 

5 

Perfect. 

78 


FLORENCE  RICHARDSON. 


Black-and-JVhite  Rat  I. 


INCHES 

TRIALS. 

8/26/07 

8 

8 

Jumped  almost  at  once  but  scrambled;  second 
and  third  good;  fourth,  seventh  and  eighth, 
scrambled;  all  others  good. 

8/27/07 

8 

6 

All  good. 

9 

5 

Second,  scrambled;  all  others  good. 

10 

10 

First,  scrambled;  all  others  good. 

12 

10 

Second  and  ninth,  scrambled;  all  others  good. 

14 

10 

First  and  tenth,  short  and  fell;  third  scrambled; 
others  good. 

8/28/07 

8 

2 

Jumped  entirely  over  both  trials. 

12 

10 

Second  and  eighth  scrambled;  others  good. 

14 

6 

First  and  third,  scrambled;  others  good. 

10 

10 

Second  and  third,  scrambled;  others  good. 

18 

9 

Third,  fifth  and  sixth,  scrambled;  ninth,  short 
and  fell;  others  good.  Was  breathless  and 
seemed  tired. 

8/29/07 

12 

2 

Both  jumps  too  long,  \vent  over  platform. 

16 

5 

First,  struck  on  north  of  platform  and  scram¬ 
bled;  distance  good  but  direction  faulty; 
third,  scrambled;  others  good. 

18 

10 

First,  too  far  north;  second,  third  and  sixth, 
scrambled  slightly;  ninth,  toward  north. 

20 

10 

Fifth,  scrambled  slightly;  others  good. 

8/30/07 

20 

10 

Sixth,  scrambled  slightly;  ninth,  short;  tenth, 
good. 

22 

10 

First  and  third,  short;  seventh  and  ninth  scram¬ 
bled. 

8/31/07 

20 

7 

Second,  scrambled;  fifth  and  seventh,  short  and 
fell. 

9/  1/07 

18 

5 

First  and  third,  scrambled  slightly. 

20 

10 

First,  second,  seventh  and  ninth,  scrambled. 

22 

10 

First,  scrambled;  third,  fell  on  south. 

Black-and- White  Rat  II. 


8/27/07 

8 

0 

Would  not  jump. 

5 

5 

Stepped  over  easily. 

6 

5 

Hopped  across. 

8 

5 

Hopped  across. 

9 

10 

First,  a  little  short;  third,  scrambled. 

10 

10 

First,  scrambled. 

12 

10 

On  seventh  trial,  fell  off  platform  in  preparing 
to  jump.  All  other  trials  good. 

14 

I 

Short  and  fell.  Tired. 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


79 


INCHES 

TRIALS. 

8/28/07 

10 

0 

Would  not  attempt  it. 

6 

5 

Very  slow  in  starting.  All  trials  good. 

8 

5 

All  good. 

10 

5 

All  good. 

12 

5 

All  good. 

14 

4 

First,  scrambled;  others  good. 

8/29/07 

12 

0 

Would  not  attempt  it.  Waited  15  min. 

10 

0 

Would  not  attempt  it.  Waited  15  min. 

8 

0 

Would  not  attempt  it.  Waited  15  min. 

5 

5 

Seems  much  afraid  and  needs  a  great  deal  of 
coaxing. 

7 

5 

Better;  all  trials  good. 

14 

5 

All  good. 

16 

5 

All  good. 

18 

5 

All  good. 

20 

2 

All  good. 

8/30/07 

16 

10 

Very  slow.  First  trial,  scrambled;  tenth,  short 
and  fell. 

8/31/07 

16 

0 

Would  not  attempt  to  jump. 

14 

5 

Timid.  First,  too  long  and  fell;  others  good. 

16 

10 

First,  scrambled;  fifth,  fell  off  the  south  side 
of  Platform  II. 

18 

5 

First,  second,  third  and  fifth  trials,  scrambled. 

Work  with  this  rat  was  here  suspended  during  an  alteration 
of  the  apparatus.  The  remainder  of  the  learning  process  was 
like  that  of  the  other  normal  rats  at  these  distances,  and  is 
not  quoted  further. 


c.  On  Blind  Rats. 

The  experimenter  attempted  to  train  four  blind  rats.  The 
animals  were  active,  and  one  of  them  had  had  experience  under 
experimental  conditions.  The  method  was  the  same  as  in  the 
tests  with  the  normal  rats,  though  the  procedure  was  much 
slower. 

The  rats  were  fed  for  several  days  upon  Platform  II,  which 
was  east  of  and  2  inches  distant  from  Platform  I.  The  animals 
were  always  placed  on  Platform  I,  facing  the  east,  and  after 
they  had  stepped  across  they  were  carefully  lifted  back  and 
set  down  facing  the  east,  upon  Platform  I.  The  normal 


8o 


FLORENCE  RICHARDSON. 


rats  acquired  their  own  orientation  relative  to  Platform  II; 
the  blind  animals  always  adjusted  themselves  for  the  jump 
in  the  position  in  which  they  had  been  set  down  upon  the  plat¬ 
form.  With  these  blind  rats  it  was  necessary  to  make  the 
increase  by  shorter  gradations,  one-fourth  or  one-half  of  an 
inch.  Two  of  the  rats  would  not  attempt  to  cross  a  space 
wider  than  they  could  reach  with  their  vibrissae.  The  notes 
on  the  behavior  of  one  of  these  is  given  below,  beginning  with 
the  distance  of  four  inches.*  The  notes  taken  on  less  distances 
contribute  nothing.  The  number  of  trials  is  not  always  given, 
as  they  had  not  been  counted  at  such  short  distances. 


Blind  Black-and-}Vhiie  Rat  on  Problem  IV. 


INCHES 

TRIALS. 

10/4/07 

4 

5 

10 

Stepped  across  to  food  platform,  always  from 
the  southeast  corner. 

Stepped  across  many  times. 

As  above. 

5i 

10 

Was  obliged  to  spring  a  little;  always  from  the 
southeast  corner. 

10/5/07 

5 

Would  not  try;  failure.  Was  obliged  to  lessen 
distance. 

10/6/07 

4i 

4 

Stepped  across  three  times  after  much  coaxing 
by  holding  food  in  front  of  him. 

5 

After  thirty  minutes  he  stepped  across  on  his 
own  initative  from  the  south-east.  Could  not 
be  coaxed  across.  Time,  forty-five  minutes. 

10/7/07 

4i 

5 

10 

Stepped  across  from  southeast  corner. 

Failure.  Will  only  reach  or  spring  as  far  as 

vibrissae  can  touch. 

The  procedure  as  noted  above  was  repeated  for  several  days 
with  little  variation  and  no  satisfactory  results.^ 

A  blind  rat  which  also  had  had  previous  experience  was 


'  This  rat  had  successfully  solved  the  previous  problems. 

*  This  rat  would  not  allow  his  fore  feet  to  leave  the  platform  unless  his  vibrissae 
reported  contact  with  some  object.  When  the  platform  was  beyond  the  reach  of 
his  vibrissae  the  experimenter  touched  their  tips  with  a  pencil,  whereupon  he  put 
out  his  fore  feet  to  step  over.  He  never  raised  his  hind  feet  until  his  fore  feet 
had  a  fi  rm  footing,  but  he  could  always  be  induced  to  make  an  attempt 
by  stimulating  his  vibrissae.  A  deodorized  glass  rod  was  used  instead  of  the 
pencil  and  it  had  the  same  effect,  showing  that  it  was  contact  alone,  and  not 
olfaction  that  tempted  him  to  make  the  effort. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


8l 


labored  with  for  many  days,  with  not  so  good  results.^  He 
would  not  step  across  when  the  platform  was  within  reach  of 
his  nose.  He  was  a  slow  rat  at  best  and  achieved  no  credit 
for  himself  in  the  previous  experiments. 

Blind  Rats  HI  and  IV  (white  untrained  females)  achieved 
signal  success  in  this  test.  Both  learned  eventually  to  jump 
distances  of  eleven  inches,  and  Rat  HI  successfully  cleared 
fifteen  inches.  A  portion  of  the  notes  on  the  behavior  of  this 
rat  is  given  here  as  they  are  of  particular  interest. 


Blind  Rat  III 


INCHES 

TRIALS. 

I I/I9/00 

Began  the  experimentation  with  the  platforms 
two  inches  apart.  Coaxed  her  across  with  a 
morsel  of  food.  She  used  vibrissae  to  locate 
the  platform.  Distance  gradually  lengthened 
to  four  inches.  This  was  the  daily  program 
for  ten  days. 

11/29/07 

10 

Stepped  across.  An  active  rat. 

5 

5 

Hopped  across.  (Had  never  been  able  to  get  a 
blind  rat  to  ‘hop’  before.) 

5 

t 

Hopped  across.  Never  turns  around.  (When 
returning  blind  rats  to  Platform  I  they  were 
always  placed  with  head  toward  food  platform . 
They  rarely  altered  this  position.) 

6 

5 

Struck  platform  squarely. 

11/30/07 

4i 

Would  not  hop  across;  obliged  to  reduce  distance 
to  four  inches  and  increased  one-half  inch  at 
a  time.  Would  not  cross  after  five  inches. 

I 2/1/07 

4 

Good. 

5 

5 

Stepped  across  at  five  inches.  Very  slow. 

5i 

5 

Hopped  after  stretching  across. 

5 

Sprang  across. 

7i 

5 

Good. 

8i 

5 

First  trial,  heels  on  angle,  others  perfect. 

9i 

5 

Same  procedure  as  above. 

lOi 

iii 

5 

First  trial,  scrambled  slightly. 

Getting  tired  and  slow.  Scrambled  in  two 
trials  and  in  fourth  trial  did  not  aim  right; 
struck  wall  at  northeast;  fell  hard  but  it  did 
not  frighten  her.  Commenced  eating  at  once 
when  placed  on  food  platform. 

^  This  rat  was  Male  I  whose  records  on  Problems  II  and  III  were  disregarded 
in  the  average  of  the  groups. 


82 


FLORENCE  RICHARDSON. 


INCHES 

TRIALS. 

I  2  - '3/07 

5i 

5 

4 

5 

Would  not  hop  across  and  could  not  step  across. 
Would  not  step  across. 

Stepped  across. 

As  above. 

5i 

4 

Coaxed  across  first  trial.  Hopped  across  in 
other  trials. 

6| 

2 

Went  entirely  over  and  struck  wall. 

4 

Went  over  platform  and  fell  first  trial,  second, 
the  same,  third,  went  to  east  side,  and  just 
saved  herself  from  falling.  Fourth  trial, 
perfect. 

00 

5 

All  perfect. 

(For  four  days  succeeding  above  there  was 
the  same  procedure  every  day.  At  the 
beginning  of  each  daily  experiment,  experi¬ 
menter  was  obliged  to  reduce  distance  to  four 
inches;  the  animals  seemed  to  carry  over 
nothing  of  advantage  from  one  day’s  experi¬ 
ence  to  the  next.  Each  day  learned  anew  to 
step  across  and  later  to  jump  to  platform.) 

12/7/07 

7 

2 

Loitered  about  for  a  long  time  then  jumped 
nearly  across  platform. 

9 

2 

First  trial,  perfect.  Second,  off  at  north. 

1 1 

2 

Perfect. 

13 

4 

First  trial,  scrambled  up  over  edge.  Second,  fell. 

15 

4 

Did  not  strike  the  platform  squarely. 

Scrambled  each  time  on  to  the  platform. 

12/8/07 

7 

10 

Jumped  over  platform  to  wall  of  canvass  con¬ 
trol  cage.  Does  not  jump  to  platform  but 
jumps  aimlessly.  Eighth  and  ninth  trials, 
struck  wall  at  distance  of  twenty  seven  inches. 

12/9/07 

12 

Jumped  across  to  wall  six  times;  distance 
twenty  inches.  Changed  distance  of  plat¬ 
form  but  would  not  jump  toward  it.  After 
dozens  of  trials  the  experimenter  gave  up  in 
despair. 

Rat  IV  had  learned  to  strike  the  platform  squarely  at  a 
distance  of  eleven  inches.  At  this  stage  of  her  training  she 
discovered  that  she  could  crawl  down  the  standard.  Sharp 
points  were  placed  about  the  edge  of  the  platform  to  prevent 
her  descent,  whereupon  she  jumped  directly  to  the  floor  below. 
Further  experimentation  was  futile. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


83 


d.  On  Anosmic  Rats. 

To  determine  accurately  that  vision  and  not  olfaction  fur¬ 
nished  the  sensory  control  of  the  adjustment,  two  anosmic  rats 
were  tested  upon  the  apparatus.^ 

The  method  of  training  of  this  animal  was  the  same  as  that 
with  the  blind  rats — the  distance  being  increased  by  half  an 
inch  at  a  time.  The  following  are  extracts  from  the  notes 
taken  on  his  behavior: 


Anosmic  Rat  I  on  Problem  IV. 


INCHES 

12/3/07 

5 

Steps  across  many  times  but  awkward  and  afraid. 

5i 

Has  to  be  coaxed  across;  slow  and  evidently  much 
disturbed  by  fear. 

52 

An  entire  failure  after  thirty  minutes  of  coaxing. 

12/13/07 

After  ten  days  of  daily  experimentation  has  made  no 
progress.  Was  stiff  with  fright  much  of  the  time  when 
urged  to  take  a  distance  greater  than  he  could  step 
across.  For  several  days  he  has  been  gnawing  fiercely 
at  the  sides  of  Platform  I  and  has  rounded  off  the 
edges  and  corners. 

12/14/07 

Failure! 

A  second  anosmic  rat  was  procured  for  the  test.  He  was 
hurried  through  the  series  with  a  fewer  number  of  trials  at 
each  distance  because  of  the  experimenter’s  apprehension  con¬ 
cerning  the  length  of  his  tenure  of  life.  He  was  in  excellent 
physical  condition  but  had  he  died  there  would  have  been  no 
possibility  of  procuring  another  anosmic  rat  in  time  for  the 
experiment.  On  the  first  day  he  succeeded  in  convincing  the 
experimenter  that  the  olfactory  stimulus  was  not  the  essential 
factor  in  the  jumping  reaction.  The  notes  quoted  below  give 
the  details  of  his  record. 


*  The  first  animal  was  the  one  which  had  formed  the  associations  involved 
in  Problems  I,  II  and  III,  though  his  time  records  in  the  last  two  problems  were 
practically  of  no  value  because  of  the  time  he  wasted  in  gnawing  the  apparatus. 


84 


FLORENCE  RICHARDSON. 


Anosmic  Rat  II  on  Problem  IV. 


INCHES 

TRIALS. 

12/6/07 

5^ 

I 

First  time  upon  platform.  Stepped  across  im¬ 
mediately. 

6 

I 

Jumped  readily  to  Platform  II. 

8 

2 

Perfect.  No  hesitation. 

9 

3 

First  trial,  scrambled;  others  perfect. 

10 

3 

Exact  repetition  of  previous  trial. 

12 

3 

Same  as  above. 

13 

3 

Scrambled,  tired.  (All  of  the  above  trials  within 
ten  minutes.) 

12/7/07 

7 

2 

Jumped  across. 

9 

2 

Perfect. 

II 

4 

First  trial,  scrambled;  others  perfect. 

13 

3 

Third  trial,  scrambled  a  little. 

15 

3 

First  trial,  scrambled;  others  perfect. 

Very  active. 

12/9/07 

7 

2 

Did  not  jump  readily  at  first,  finally  coaxed 
across.  Struck  squarely. 

9 

2 

Perfect. 

II 

3 

First  trial,  scrambled;  others  good. 

13 

3 

Perfect. 

15 

Short,  and  fell  twice;  afraid,  put  him  up. 

12/12/07 

6 

I 

Would  not  jump  at  first. 

8 

I 

Same  as  above. 

14 

4 

First  and  second  trials,  scrambled;  other  trials 
perfect. 

15 

5 

As  above.  (Is  lame  in  left  hind  leg.) 

12/15/07 

16 

5 

Slow.  First  trial,  struck  on  south  side.  Second, 
same  but  nearer  center. 

18 

5 

First  and  third  trials,  scrambled  slightly. 

20 

3 

Second  trial,  struck  platform,  but  fe’l  off. 

22 

7 

Fourth  trial,  scrambled;  sixth,  little  short  and  fell. 
Tired. 

The  behavior  of  this  rat  in  the  above  test  was  in  every  respect 
like  that  of  the  normal  animals.  He  had  had  previous  experi¬ 
ence  on  Problem  I,  and  was  apparently  undisturbed  emotion¬ 
ally  by  the  conditions  of  the  experiment.  He  learned  to  jump 
his  maximum  distance  in  a  shorter  time  than  did  any  other 
white  rat,  though  to  what  extent  his  facility  was  due  to  fear¬ 
lessness  and  to  the  fact  that  the  experimenter  lost  no  time  in 
lengthening  his  distances  cannot  be  estimated. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


85 


ii.  Summary. 

1.  Five  normal  white  rats,  the  three  normal  black-and- 
white  rats,  and  one  anosmic  animal  were  able  to  learn  to 
jump  successfully  a  distance  of  at  least  22  inches.  These 
adjustments  were  acquired  with  comparative  ease.  One  other 
normal  white  rat  learned  to  jump  as  long  a  distance  as  22 
inches  with  difficulty,  and  another  did  not  learn  to  jump 
more  than  15  inches.  No  normal  rat  failed  to  learn  to  jump. 
Two  of  the  blind  rats  (III  and  IV)  achieved  success  in  this  test. 
Both  learned  to  jump  a  distance  of  ii  inches.  One  (Rat  III) 
learned  to  jump  a  distance  of  15  inches.  Here  the  coordina¬ 
tion  broke  down  apparently  on  account  of  the  fact  that  a  large 
percentage  of  her  jumps  were  inaccurate;  she  had  to  scramble 
onto  the  platform  much  of  the  time,  and  she  often  failed  utterly 
to  strike  it  and  consequently  fell.  Rat  IV  learned  to  jump 
a  distance  of  ii  inches,  but  the  coordination  broke  down 
upon  her  discovery  that  she  could  crawl  down  the  standard. 

2.  One  anosmic  and  two  blind  rats  were  utter  failures. 
Two  were  willing  to  step  across  to  the  second  platform,  but 
they  were  either  unable,  or  else  refused,  to  jump.  The  fail¬ 
ure  of  the  anosmic  rat  was  probably  due  to  the  fright  occa¬ 
sioned  by  the  unusualness  of  the  conditions  of  the  experi¬ 
ment  and  not  to  any  lack  of  proper  sensory  control.  Under 
any  other  circumstances  he  ran  about  naturally  in  search  of 
food.  The  blind  animals  did  not  seem  to  be  emotionally 
disturbed,  and  hence  their  failure  was  probably  referable  to  a 
lack  of  adequate  stimulus. 

3.  Effect  of  Changing  Direction  in  which  ^ump  Must  be 

Taken. 

In  order  to  determine  more  accurately  the  sensory  factors 
involved  in  the  coordinaton  it  was  decided  to  change  the 
position  of  the  apparatus  and  thereby  the  direction  in  which  the 
animal  has  to  jump.  It  would  seem  that  if  the  rats  can  accom¬ 
modate  at  once  to  changes  in  the  direction  of  Platform  II,  some 
distance  receptor  must  be  operative.  Such  a  test  might  also 
show  the  possible  presence  of  some  ‘directional’  factor  which 


86 


FLORENCE  RICHARDSON. 


is  not  visual  in  character.  Three  white  rats  had  been  trained 
to  jump  distances  gradually  increasing  from  6  to  30  inches. 
These  longer  distances,  as  has  been  noted,  were  too  great  to 
permit  of  accurate  adjustment  on  the  part  of  the  rat,  and  they 
demanded  an  unnecessary  expenditure  of  energy.  Accordingly, 
a  record  of  80  per  cent  of  perfect  coordinations  at  22  inches 
was  chosen  as  a  standard  of  efficiency  to  be  attained  before 
the  animals  should  be  tested  with  the  apparatus  turned  in 
another  direction.  Three  white  rats  had  reached  this  degree 
of  capability. 

The  apparatus  was  then  so  adjusted  that  the  rat  must  jump 
22  inches  to  the  south  for  food.  To  the  surprise  of  the  observ¬ 
ers,  two  of  the  rats  continued  to  jump  toward  the  east  for 
twenty  successive  trials  each.  The  third  rat  jumped  twice 
toward  the  south,  though  he  did  not  jump  far  enough  to  land 
on  the  platform;  at  the  third  trial  he  settled  down  comfortably 
on  the  starting  platform  and  refused  to  jump. 

Acting  on  the  possibility  that  the  two  rats  were  jumping 
toward  their  cages — which  were  to  the  east — or  reacting  to 
other  features  in  the  environment  of  a  visual  or  olfactory 
character,  the  conditions  of  the  experiment  were  radically 
changed. 

A  cabinet  4  feet  by  4  feet,  by  6  feet  was  built.  The  frame¬ 
work  was  of  2  by  4  inch  timber,  the  sides  and  top  of  white 
canvas.  The  cabinet  was  illuminated  by  a  32  c.p.  electric 
light  fastened  to  the  center  of  the  top  of  the  cabinet.  The 
visual  and  olfactory  conditions  of  the  environment  were  thus 
rendered  subject  to  control.  At  this  time  the  apparatus  it  elf 
was  improved.  The  connecting  rod  was  made  of  i  inch  pipe, 
clamped  in  iron  end  supports.  The  uprights  supporting  the 
platforms  were  of  |  inch  steel,  clamped  at  right  angles  to  the 
base.  One  of  the  uprights  consisted  of  two  18  inch  steel  bars 
clamped  together  so  that  the  height  of  platform  it  bore 
might  be  varied  from  18  to  30  inches.  The  apparatus  in  this 
form  was  much  more  easily  adjusted  to  horizontal  changes  in 
distance.  It  also  possessed  the  added  advantage  of  offering 
any  possible  adjustment  in  height. 

W  hile  working  with  the  wooden  platform  the  feet  of  the 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


87 


animal  became  sore.  In  making  such  leaps  as  are  necessary 
in  these  tests — covering  sometimes  a  distance  of  24  inches — 
the  rat  lands  heavily  upon  the  forefeet.  This  might  have  been 
the  cause  of  the  soreness.  The  platforms  were  later  covered 
with  cork  matting,  and  this  in  turn  with  soft  leather.  The 
whole  was  then  painted  light  gray.  Though  the  paint  added 
somewhat  to  the  resistance  of  the  surface  the  rats  had  little 
difficulty  thereafter  with  soreness  of  the  feet. 

After  the  cabinet  had  been  constructed,  the  rats  which  had 
learned  to  jump  on  the  old  apparatus  were  tested  in  the  new 
one.  There  had  been  an  interval  of  three  weeks  since  their 
last  trials  and  several  days’  training  was  necessary  to  bring 
them  up  to  their  former  standard  of  accomplishment.  While 
training  the  rats  the  experimenter  remained  within  the  cabinet 
to  catch  them  when  they  fell  and  to  feed  them  immediately 
after  they  reached  the  platform.  After  the  habit  had  been 
reestablished  and  it  was  desired  to  test  the  animal  with  the 
apparatus  in  a  new  position,  the  rat  was  observed  from  without 
through  a  slit  in  the  canvas.  The  position  of  the  observer 
outside  the  cage  was  also  changed  in  every  test,  in  order  that 
the  rat  might  not  associate  the  sound  of  the  experimenter’s 
movements  with  the  direction  in  which  the  jump  must  be 
taken. 

The  possibility  of  an  olfactory  stimulus  was  here  minimized 
by  allowing  no  food  in  the  cabinet.  The  rat  was  fed  from  the 
experimenter’s  hand  after  the  jump,  and  Platform  II  was 
kept  clean,  and  newly  covered,  top  and  sides,  with  black-and- 
white  checkered  cloth — to  add  greater  character  to  the  visual 
stimulus. 

Each  day  before  the  apparatus  was  turned  the  rat  was  given 
five  or  more  tests  in  jumping  toward  the  east  which  during 
the  previous  training  had  been  the  constant  direction.  If 
80  per  cent  of  the  trials  were  perfect,  the  cabinet  and  appa¬ 
ratus  were  rotated.  This  change  necessitated  jumping  to  the 
south,  the  north,  or  the  west,  as  the  alteration  might  demand, 
in  order  to  reach  Platform  II.  Care  was  taken  to  place  the 
rat  on  Platform  I  in  different  positions  during  the  various 
trials,  so  that  the  initial  position  would  be  no  cue  to  the  essen¬ 
tial  orientation. 


88 


FLORENCE  RICHARDSON. 


1.  Statement  of  Results. 


a.  On  Normal  White  Rats. 


The  records  of  the  normal  white  rats  in  this  test  are  given 
below. 


White  Female  /, 


POSITION  OF 

PLATFORM  II. 

12/9/07 

East  22  in. 

Ten  trials,  80  per  cent  perfect. 

South. 

Perfect. 

West. 

Refused  to  jump. 

North. 

Refused  to  jump. 

West. 

Jumped  south. 

East. 

Refused  to  jump. 

12/10/07 

East. 

Eight  trials,  all  good. 

North. 

Went  entirely  over  platform  to  north,  and  struck 
canvas. 

West. 

Refused  to  jump. 

South. 

Fell  off  platform  in  preparing  to  jump  toward 
south,  and  was  frightened.  No  other  tests 
today. 

1 2/1 1/07 

East. 

Five  trials,  perfect. 

West. 

Perfect. 

South. 

Jumped  east. 

North. 

Perfect. 

West. 

Jumped  south. 

12/12/07 

North. ^ 

Jumped  east. 

West. 

Jumped  south. 

12/13/07 

South. 

Jumped  east. 

12/14/07 

South. 

Jumped  east. 

North. 

Slow  and  confused.  Will  not  jump. 

12/15/07 

West. 

Refused  to  jump,  apparently  much  confused. 

12/16/07 

East. 

Same  as  above. 

'  Platform  II  was  not  placed  at  the  east  for  the  first  trial,  as  the  animal 
exhibited  a  tendency  to  jump  east  habitually,  and  it  was  feared  that  this  position 
might  unduly  emphasize  the  tendency. 


A  STUDT  OF  SENSOR!'  CONTROL  IN  THE  RAT. 


89 


JVhite  Male  II. 


POSITION  OF 

PLATFORM  II. 

12/6/07 

East  24  in. 

Ten  trials,  80  per  cent  perfect. 

South,  22  in. 

One  trial,  immediate  and  perfect  accommoda¬ 
tion. 

West,  24  in. 

One  trial,  perfect,  jumped  at  once. 

North,  24  in. 

Direction  perfect,  but  jumped  too  short. 

East,  24  in. 

One  trial,  perfect. 

Apparatus  turned  but  not  cabinet. 

North,  24  in. 

One  trial,  perfect. 

North,  24  in. 

One  trial,  perfect. 

East,  24  in. 

One  trial,  went  slightly  to  right  of  platform, 
grazing  the  side. 

West,  24  in. 

One  trial,  perfect. 

12/7/07 

East,  24  in. 

Ten  trials,  and  but  30  per  cent  perfect.  Jumped 
down  toward  bottom  of  apparatus.  Did 
not  try  to  jump  to  platform. 

JFhite  Male  III. 


12/6/07 

East,  24  in. 

Fivetrials,  scrambled  slightly  each  time.  Animal 
is  ill  and  weak. 

North,  24  in. 

One  trial,  right  direction  but  short. 

South,  24  in. 

One  trial,  same  as  above.  Did  not  work  again 
and  died  soon  after. 

Two  of  the  three  rats  jumped  to  the  platform  in  the  new 
position  at  every  test  on  the  first  trial.  The  third  rat,  Female 
I,  jumped  to  the  platform  which  was  toward  the  south  on  the 
first  trial,  but  on  the  second,  third,  and  fifth  trials  she  refused 
to  jump.  On  the  fourth  she  jumped  south  again  when  she 
should  have  jumped  east.  On  the  first  trial  for  the  second  day 
with  platform  north  she  jumped  to  it  at  once,  then  refused  to 
jump  the  next  time.  On  the  first  trial  on  the  third  day  the 
adjustments  were  perfect,  though  on  two  of  the  later  trials 
she  jumped  in  the  wrong  direction.  On  the  fourth,  fifth  and 
sixth  days  she  made  no  perfect  coordinations,  either  jumping 
to  the  east,  with  one  exception,  or  refusing  to  jump  at  all. 
The  tests  had  to  be  discontinued  because  of  her  disinclination 
to  leave  Platform  I.  She  would  jump  toward  the  east  with 


go 


FLORENCE  RICHARDSON. 


the  platform  in  that  direction  but  not  otherwise.  In  the  case 
of  Rat  II,  also,  there  was  a  tendency  for  the  coordination  to 
break  down  under  the  changed  conditions,  as  this  rat  took  to 
jumping  toward  the  base  of  the  opposite  standard,  and  could 
not  thereafter  be  induced  to  jump  to  the  platform.  This  series 
was  necessarily  abbreviated  on  that  account. 

b.  On  Normal  Black-and-White  Rats. 

Three  black-and-white  rats  were  given  the  same  test.  They 
had  attained  the  necessary  standard  of  efficiency,  i.  e.,  8o 
per  cent  of  perfect  coordinations  at  22  inches.  The  following 
are  from  the  notes  taken  on  this  series. 


Black-and- White  Female  /. 


POSITION  OF 

PLATFORM  II. 

10/29/07 

East,  22  in. 

Five  trials;  100  per  cent  perfect. 

South. 

One  trial,  perfect. 

West. 

Jumped  southeast  five  times  in  succession 
apparently  at  a  shadow^  caused  by  the  joining 
of  the  canvas  strips. 

10/30/07 

East. 

Six  trials,  80  per  cent  perfect.  Shows  tendency 
to  jump  toward  northeast. 

South. 

Two  trials,  first,  slightly  to  east  of  south. 
Second,  perfect. 

West. 

Two  trials,  first;  slightly  to  south  of  west;  second 
perfect. 

South. 

One  trial,  jumped  to  wall  on  south. 

East. 

Two  trials,  first,  jumped  to  south ;  second  to  east. 

West. 

Two  trials,  first,  southwest;  second,  perfect. 

North. 

Refused  to  jump. 

II/I/07 

East. 

One  trial,  perfect. 

North. 

Jumped  northeast  to  canvas. 

Same  relative  direction. 

West. 

Jumped  southeast. 

North. 

Jumped  northeast  to  canvas. 

I 1/5/07 

South. 

Jumped  northeast  to  canvas.  Jumped  to  wall 
repeatedly  but  not  to  platform .  T ests  discon¬ 
tinued. 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


9^ 


Black- and- White  Female  II. 


POSITION  OF 

platform  II. 

I r/30/07 

East. 

Five  trials,  60  per  cent  perfect,  others  good. 

South. 

One  trial,  perfect. 

North. 

One  trial,  perfect. 

South. 

One  trial,  perfect. 

10/31/07 

East. 

One  trial,  perfect. 

South. 

One  trial,  perfect. 

West. 

One  trial,  perfect. 

North. 

One  trial,  perfect. 

West. 

One  trial,  perfect. 

North. 

One  trial,  perfect. 

u/I/07 

East. 

One  trial,  perfect. 

West. 

One  trial,  perfect. 

South. 

One  trial,  perfect. 

North. 

One  trial,  perfect. 

TURNED  APPARATUS  BUT  NOT  CABINET. 

I 1/2/07 

South. 

One  trial,  direction  perfect  but  distance  short. 

West. 

One  trial,  rat  confused.  Put  back. 

1 1/3/07 

East. 

One  trial,  direction  correct,  distance  short. 

North. 

One  trial,  perfect. 

West. 

One  trial,  perfect. 

South. 

One  trial,  perfect. 

Black-and-White  Female  III. 


11/19/07 

East,  22  in. 

Ten  trials,  80  per  cent  perfect. 

South. 

One  trial,  good. 

West. 

One  trial,  good. 

North. 

One  trial,  good. 

East. 

Eight  trials,  75  per  cent  perfect. 

North. 

One  trial,  perfect. 

South. 

One  trial,  perfect. 

West. 

One  trial,  jumped  to  floor. 

11/21/07 

Very  active  rat;  gets  innervation  before  muscu¬ 
lar  accommodation,  consequently  makes  ran¬ 
dom  leaps. 

11/24/07 

Will  jump  only  to  floor.  Tried  several  devices 
to  prevent  this,  but  none  successful.  Series 
discontinued. 

The  black-and-white  rats,  like  the  white  ones,  reached  a 
point  in  the  tests  where  the  accommodation  to  the  distance  and 
the  direction  broke  down  completely,  though  it  did  not  break 


92 


FLORENCE  RICHARDSON. 


down  SO  soon.  These  rats  had  not  been  at  work  at  the  test 
as  long  as  the  white  animals  which  had  been  trained  upon  the 
old  apparatus  and  retrained  upon  the  new. 

c.  On  Anosmic  Rat. 

The  anosmic  rat  had  just  reached  the  necessary  maximum 
of  22  inches  before  the  test  with  apparatus  rotated  could  be 
made.  He  had  been  given  two  trials  with  the  apparatuschanged. 
Through  some  mishap  on  the  part  of  the  laboratory  attendant 
the  rat  gained  his  liberty,  and  was  not  seen  thereafter.  His 
records  for  the  two  trials  follow: 


Record  of  Anosmic  Rat:  Position  of  A pparatus  Variable. 


POSITION  OF 

PLATFORM  IT. 

TRIALS. 

12/15/07 

East 

7 

Fourth  trial,  scrambled;  sixth,  short  and 
fell.  Seems  tired. 

South. 

I 

Slow,  but  accurate. 

West. 

I 

Good.  Very  slow. 

ii.  Summary. 

1.  Four  of  the  six  rats  were  able  to  direct  their  jumps 
equally  well,  regardless  of  the  direction  in  which  the  jump 
must  be  taken.  The  other  two  animals  were  able  to  accom¬ 
plish  this  in  about  50  per  cent  of  their  trials. 

2.  These  two  other  rats  were  by  no  means  failures  on  the 
problem.  One  of  them.  White  Female  I,  jumped  to  Platform 
H  which  was  south  at  the  first  trial.  She  had  always  previ¬ 
ously^  jumped  to  the  east.  After  this  trial  she  often  refused 
to  make  the  effort.  Of  the  twelve  trials  in  which  she  made  an 
effort,  she  was  five  times  successful  in  the  direction  of  her 
jump,  and  failed  seven  times.  Of  these  seven  failures,  four 
were  jumps  to  the  east  and  three  to  the  south. 

The  remaining  rat,  Black-and-White  Female  I,  did  not 
attempt  to  jump  toward  Platform  H  when  it  was  turned  to 
the  south,  but  jumped  five  times  in  succession  to  a  point  in 


A  STUDr  OF  SENSORT  CONTROL  IN  THE  RAT. 


93 


the  wall  of  the  cabinet  where  one  width  of  canvas  overlapped 
another,  and  wriggled  through,  emerging  on  the  outside  of 
the  cabinet.  On  the  following  day  she  jumped  in  the  direction 
of  Platform  II,  five  trials,  though  she  did  not  always  strike  it 
squarely  on  the  first  trial,  then  missed  by  jumping  south  when 
she  should  have  jumped  east.  Soon  after  she  failed  to  make 
any  attempt  to  jump  to  Platform  II,  but  jumped  to  the  walls 
instead. 

Effect  of  Altering  Distances  Between  Platforms, 
a.  Effect  of  Altering  Horizontal  Distance. 

During  the  training  period  it  became  evident  that  the  rats 
were  unable  to  accommodate  with  any  degree  of  ease  to  a 
distance  which  was  shorter  than  the  one  for  which  they  had 
established  a  habit.  It  will  be  remembered  that  the  rats  had 
to  start  any  given  day’s  work  with  a  jump  which  was  slightly 
.  shorter  than  the  maximum  jump  which  they  had  been  able 
to  attain  the  day  before.  Under  such  conditions  the  animals 
would  often  over-innervate  for  the  first  few  trials  and  jump 
entirely  over  Platform  II. 

A  series  of  tests  was  undertaken  to  determine  (i)  the  num¬ 
ber  of  trials  necessary  for  and  (2)  the  sensory  factors  involved 
in  a  readjustment  to  shortened  distances.  The  experiments 
are  not  so  numerous  as  had  been  planned  by  reason  of  the 
fact  that  the  coordination  had  broken  down  in  many  of  the 
animals.  The  preceding  section  shows  that  changing  the  direc¬ 
tion  in  which  the  jump  must  be  taken  tended  to  disintegrate 
the  coordination  with  all  the  animals  but  one.  If  this  had 
been  predictable,  the  present  experiments  would  have  preceded 
those  of  the  last  section. 

The  tests  here  reported  upon  were  made  in  the  cabinet 
under  conditions  closely  similar  to  those  reported  in  the  last 
section.  The  food,  however,  consisting  of  sunflower  seed,  was 
placed  in  a  small  receptacle  which  hung  from  the  far  edge  of 
Platform  II.  It  afforded  no  visual  and  probably  little  olfac¬ 
tory  stimulation. 


94 


FLORENCE  RICHARDSON. 


Before  decreasing  the  distance  between  the  platforms  the 
now  thoroughly  experienced  animals  were  allowed  to  establish 
a  habit  for  the  distance  of  twenty-two  inches.  The  distance 
was  then  shortened  and  the  effort  of  the  animal  to  accommodate 
to  it  was  recorded.  The  notes  below  show  the  changes  made 
and  the  essential  features  of  the  animal’s  behavior. 

i.  Statement  of  Results. 

a.  On  Normal  White  and  on  Normal  Black-and-White  Rats. 

The  results  on  the  white  and  on  the  black-and-white  rats 
are  given  together,  since  the  numbers  are  too  small  to  justify 
a  separation.  Only  three  animals  could  be  used  for  the  pur¬ 
poses  of  the  test.  The  notes  on  the  behavior  of  Female  III 
are  given  below. 

White  Female  III. 


INCHES. 

TRIALS. 

12/31/07 

22 

5 

First  and  second,  to  left  of  center  of  platform; 
third,  fourth  and  fifth,  good. 

f /I/08 

16 

5 

First,  long,  went  over  platform;  second,  struck 
but  slid  off  far  edge;  third  and  fourth,  good; 
fifth,  perfect,  struck  squarely. 

8 

8 

First,  entirely  over  and  struck  opposite  wall  of 
cabinet;  second,  third  and  fourth,  shorter  but 
entirely  over;  fifth,  like  first;  sixth,  seventh 
and  eighth,  entirely  over. 

1/2/08 

22 

5 

First  short,  about  one-half  of  distance  to  plat¬ 
form;  other  four  trials  good. 

8 

5 

First,  second,  third  and  fourth,  long;  fifth, 
struck  platform  in  passing  but  slid  off. 

1/3/08 

22 

5 

First  trial,  short;  second,  landed  on  the  right 
side  of  the  platform;  fourth,  scrambled;  fifth, 
good. 

16 

5 

First,  struck  platforjn  in  passing  over;  second, 
struck  squarely;third  and  fourth,  scrambled; 
fifth,  good. 

8 

I 

Went  entirely  over  at  first  trial  and  refused  to 
jump  again. 

1/4/08 

22 

0 

Failure — refused  to  jump. 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


95 


White  Male  1. 


INCHES. 

TRIALS. 

8/24/07 

22 

4 

All  perfect. 

12 

10 

First  trial,  second  and  third,  entirely  over; 
fourth,  his  hind  feet  and  tail  grazed  plat¬ 
form  as  he  went  over;  fifth  and  sixth,  over, 
butshorterand  struck  platform  with  his  tail; 
seventh  and  eighth,  grazed,  platform  with  all 
fours  as  he  went  over;  ninth,  struck  plat¬ 
form  on  far  side  and  slipped  oflF ;  tenth,  landed 
on  further  side  of  platform  but  stayed  on. 

8/25/07 

22 

0 

Rat  refused  to  jump;  was  evidently  not  well. 
The  animal  had  a  sore  foot  and  the  tests  were 
discontinued.  It  died  soon  after. 

Black-and-White  Female  III  was  experimented  with  and 
her  records  follow. 

Black-and- White  Female  III. 


INCHES. 

TRIALS. 

10/14/07 

22 

5 

First  trial,  scrambled;  other  four  trials  per¬ 
fect. 

16 

5 

Jumped  entirely  over  platform  at  every  trial. 

10/15/07 

22 

0 

Refused  to  jump. 

16 

0 

Refused  to  jump. 

8 

22 

Went  over  platform  at  every  trial;  seemed 
to  be  jumping  about  22  inches. 

1 1/4/07 

22 

5 

All  good. 

8 

10 

All  much  too  long. 

16 

10 

First  trial,  shorter  than  22  inches  but  entirely 
over  platform;  second,  shorter  than  first; 
third,  feet  grazed  plane  as  she  went  over; 
fourth,  same;  fifth,  struck  but  slid  off; 
sixth, good;  seventh  and  eighth,  like  fifth; 
ninth  and  tenth,  good. 

h.  Effect  of  Altering  both  Horizontal  and  Vertical  Distances. 

Up  to  this  time  the  platforms  had  been  at  the  same  height, 
so  that  the  main  direction  of  the  necessary  jump  was  horizontal. 
The  apparatus  was  now  adjusted  so  that  Platform  II  was  6 
inches  higher  than,  and  at  a  distance  of  i6  inches  from  Plat¬ 
form  II.  Several  rats  were  tested  under  this  condition,  but 


96 


FLORENCE  RICHARDSON. 


the  upward  spring  seemed  almost  impossible  of  acquisition 
and  no  rat  was  successful.  The  attempt  to  jump  upward  was 
unmistakably  made,  with  the  result  that  the  animal  sometimes 
struck  with  considerable  force  against  the  standard  or  the  under 
side  of  the  platform,  or  else  landed  on  the  wall  opposite  or 
upon  the  floor.  No  long  continued  effort  was  made  to  train 
the  few  remaining  jumpers  lest  the  repeated  errors  should  ren¬ 
der  them  unfit  for  further  experimentation. 

The  apparatus  was  then  re-adjusted  so  that  Platform]II|was 
10  inches  below  the  level  of  and  i6  inches  distant  horizontally 
from  Platform  I. 

/.  Statement  of  Results. 

a.  On  Normal  White,  and  on  Normal  Black-and-White  Rats. 


The  notes  on  the  behavior  of  the  two  remaining  animals 
follow. 

White  Female  III. 


INCHES. 

TRIALS. 

1/6/08 

22 

5 

All  good. 

/  16  Horizontal 

5 

Was  slow  in  preparing  to  jump;  seemed 

\  10  Vertical 

ready  to  spring  several  times  before 
she  finally  essayed  it.  Looked  down¬ 
ward  toward  the  platform.  First, 
landed  on  left  margin  of  platform; 
second,  third,  fourth  and  fifth,  good. 

1/7/08 

/ 16  H. 

5 

Same  slow  and  elaborate  preparations 

\  10  V. 

as  yesterday.  First  and  second,  per¬ 
fect;  third,  scrambled  slightly;  fourth 
and  fifth,  perfect. 

/  8  H. 

5 

Slow  in  starting.  Jumped  downward 

\io  V. 

but  considerably  over  the  platform. 
Did  not  seem  at  any  trial  to  shorten 
her  jumps  from  those  of  yesterday. 
All  trials  a  failure. 

1/8/08 

/  8  H. 

\ioV. 

5 

Behavior  as  before,  only  slower.  No 
successes. 

1/9/08 

/  8  H. 

2 

After  long  intervals  she  jumped  twice 

\io  V. 

with  results  as  above;  then  seemingly 
discouraged  she  settled  down  for  an 
hour  and  refused  to  make  any  efforts. 

/8  H. 

\io  V. 

I/I0/08 

0 

Would  make  no  effort. 

A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


97 


Black-and- White  Female  II. 


INCHES. 

TRIALS. 

1/5/07 

22  H. 

5 

All  trials  perfect. 

i  22  H. 

\  10  V. 

5 

Jumped  down  and  struck  platform 
squarely,  but  angle  was  so  great  that 
she  slipped  off;  second,  struck  squarely 
and  slid  but  did  not  fall  off;  third, 
fourth  and  fifth,  perfect  and  with  less 
force. 

/ 16  H. 

\io  V. 

10 

First,  entirely  over;  second,  struck  plat¬ 
form  with  hind  legs  and  tail  as  she 
passed;  third,  shorter  but  still  over; 
fourth,  fifth  and  sixth,  landed  but  slid 
off  by  reason  of  momentum;  seventh, 
eighth,  ninth  and  tenth,  struck  squarely 
on  platform  and  did  not  slide. 

1/6/07 

/  16  H. 

6 

First,  struck  platform  with  hind  feet  only; 

1  10  V. 

others  good. 

/  8  H. 

\io  V. 

10 

First  and  second,  over;  third,  over  but 
struck  in  passing;  fourth,  shorter; 
other  six  trials  entirely  over. 

1/7/07 

/  8  H. 

\io  V. 

20 

No  nearer  coordination  than  before. 

1/8/07 

j  8  H. 

8 

As  yesterday;  all  trials  were  failures. 

\io  V. 

The  platform  was  then  moved  out  to  the 
point  v/hich  would  intersect  her  leap. 
The  distance  proved  to  be  15  inches. 

/15  H. 

\io  V. 

6 

First,  struck  platform  with  tail;  second, 
struck  platform  on  right  side  and  fell 
off';  third,  struck  on  right  side  but 
stayed  on;  fourth,  jump  a  little  long 
but  stayed  on  platform;  fifth,  struck 
it  and  fell  off;  sixth,  good. 

II.  Summary. 

I.  No  rat  was  able  to  make  the  adjustment  when  the  dis¬ 
tance  was  changed  from  22  inches  to  8  inches  in  a  rea¬ 
sonable  number  of  trials.  One  rat  failed  after  seventy 
trials.  All  animals  were  able  to  adjust  without  great  difficulty 
to  the  change  from  22  to  i6  inches  apparently  by  means  of  a 
trial  and  error  method.  An  average  of  about  one  trial  was 
necessary  in  order  to  effect  this  readjustment.  When  the  dis- 


98 


FLORENCE  RICHARDSON. 


tance  was  shortened  the  animals  always  jumped  too  far  on  the 
first  trials. 

2.  In  the  few  cases  where  the  distance  was  suddenly 
lengthened  the  jump  was  usually  too  short  on  the  first  trials. 
It  was  impossible  to  compare  the  ease  of  the  readjustment  to 
the  lengthened  distances,  with  that  for  the  shortened  distances, 
by  reason  of  the  fact  that  the  animals  were  taught  to  jump 
long  distances  by  gradually  increasing  the  distance  between 
the  platforms.  The  adjustment  to  an  increased  distance  was 
thus  more  habitual  than  that  to  a  shortened  distance. 

3.  The  animals  were  able  to  adjust  successfully  at  once  for 
the  lowered  position  at  16  inches.  They  could  adjust  for  a 
lowered  and  shortened  distance  more  easily  than  for  merely 
the  shortened  distance.  They  could  not,  however,  adjust  to 
the  lowered  and  shortened  position  at  8  inches.  It  was  evident 
that  they  were  making  the  effort  but  they  invariably  jumped 
out  too  far. 


5.  CONCLUSIONS. 

The  purpose  of  the  foregoing  tests  was  to  estimate  the 
importance  of  vision  in  the  coordination  required  in  jumping. 
Three  aspects  of  the  coordination  as  a  whole  were  considered : 
a  Learning  to  jump  a  given  distance  when  the  direction  of 
the  jump  was  constant;  b  the  effect,  after  the  jump  under 
constant  conditions  had  become  automatized,  of  changing  the 
distance  of  the  jump,  the  direction  remaining  constant  as 
before;  and  c  the  effect  of  changing  the  distance  and  the  direc¬ 
tion  of  the  jump  in  either  the  horizontal  or  vertical  planes,  or 
in  both.  The  data  gathered  from  the  various  experiments 
seem  to  justify  the  following  general  conclusions,  stated  in  the 
order  of  the  problems  as  indicated  above. 

a.  Learning  to  Jump — Direction  Constant. 

The  results  indicate  that  the  loss  of  vision  in  some  way 
interferes  with  learning  to  jump  long  distances  and  greatly 
decreases  the  ease  and  rapidity  in  the  acquisition  of  the  coor¬ 
dination  for  short  distances.  In  the  case  of  the  two  blind 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


99 


individuals  which  failed,  it  seemed  that  some  element  was 
lacking  which  was  essential  to  the  initiation  of  the  act.  The 
fact  that  two  blind  rats  learned  to  jump  even  the  shorter  dis¬ 
tances,  and  that  the  normal  animals  had  to  accommodate  by 
a  trial  and  error  method  to  sudden  increases  and  decreases  in 
the  distance  between  platforms,  indicates  that  up  to  a  certain 
point,  other  than  visual  factors  are  concerned  in  these  adaptations 
to  a  distant  stimulus.  The  blind  animals,  unlike  the  normal 
animals,  did  not  move  about  when  placed  facing  the  east  on 
Platform  I :  they  were  given  their  orientation  and  retained  it. 
The  normal  animals  moved  about  on  the  platform  so  continu¬ 
ously  that  the  experimenter  made  no  effort  to  put  them  down 
in  a  relatively  constant  position.  The  fact  that  their  orientation 
was  given  to  the  blind  rats  was  probably  the  reason  of  their 
success.  An  attempt  was  to  have  been  made  to  test  this  factor 
by  changing  the  initial  position,  but  the  coordination  disin¬ 
tegrated  before  the  test  could  be  made.  Certainly  the  experi¬ 
ments  on  the  process  of  learning  to  jump  are  not  decisive  in 
indicating  what  role  vision  plays  in  this  coordination. 

It  has  been  shown  that  the  tactual,  kinaesthetic  and  olfactory 
senses  are  able  to  mediate  accurate  adjustments  to  short  dis¬ 
tances  even  in  the  absence  of  visual  impulses.  The  separate 
role  played  by  each  of  these  senses  in  the  case  of  the  blind 
animals  has  not  been  determined.  Judging  from  the  tests 
upon  the  anosmic  animals  it  would  appear  that  olfactory  stimuli 
can  be  dispensed  with  both  during  the  acquisition  of  the  habit 
and  at  all  later  times.  Touch,  as  a  partially  controlling  factor, 
does,  however,  enter  into  the  early  adjustments  of  the  blind 
animals,  since  they  will  more  readily  form  the  habit  of  jumping 
if  the  snout  or  vibrissae  are  stimulated  by  the  platform  to  which 
the  animal  has  to  jump.  This  latter  statement  applies  in  some 
degree  at  least  even  to  the  animals  possessing  vision.  Once 
the  habit  is  formed,  however,  the  initial  tactual  impulses  can 
be  dispensed  with. 

In  regard  to  the  function  of  kinaesthetic  impulses  in  the  case 
of  the  blind  animals,  it  seems  safe  to  affirm  that  they  soon 
come  to  usurp  whatever  function  tactual  impulses  from  the 
snout  and  vibrissae  exert  in  the  learning  process.  They  soon 


lOO 


FLORENCE  RICHARDSON. 


become  the  only  indispensable  means  of  control  in  the  blind 
animal  for  such  short  jumps  as  they  were  able  to  accomplish^ 

b.  Effect  of  Lengthening  or  Shortening  the  Jump,  Direction 

Constant. 

From  the  experiments  on  p.  93  it  follows  that  the  change 
in  visual  impulses  conditioned  by  lengthening  or  shortening 
the  distance  between  the  platforms  is  not  adequate  to  effect 
the  change  in  innervation  necessary  for  a  successful  coordina¬ 
tion.  Lengthening  or  shortening  the  distance  between  the 
platforms  may  bring  about  a  change  in  accommodation  and 
in  convergence  (kinaesthetic  factors)  and  certainly  occasions  a 
change  in  the  intensity  of  the  visual  impulses  and  the  size  of 
the  area  of  the  retinal  elements  which  receive  the  stimulation 
(change  in  visual  impulse  proper).  In  the  case  of  these  types 
of  animals,  monkey,  cat,  etc.,  where  adjustments  under  similar 
conditions  are  accurate,  the  above  noted  changes  in  the  sen¬ 
sory  complex  in  all  probability  are  sufficient  to  bring  about  the 
proper  modification  in  the  motor  discharge.  In  the  case  of 
the  rat,  however,  these  delicate  changes  in  sensory  stimulation 
are  inadequate  to  modify  the  habitual  motor  response.  The  rat 
apparently,  in  order  to  accommodate  to  the  changes  in  distance, 
must  make  trial  movements,  that  is,  fnust  establish  a  habit  of 
jumping  a  given  distance.  Any  change  in  the  distance  calls 
for  learning  factors  similar  to  those  already  discussed  on  p. 
72.  It  is  evident  that  by  means  of  these  trial  jumps  the  animal 
is  bringing  into  play  the  large  muscles  of  the  body  (as  contrasted 
with  the  eye  muscles  and  the  ciliary  muscle)  and  is  thereby 
gaining  a  control  over  the  motor  area  which  it  is  perhaps  impos¬ 
sible  to  obtain  by  the  visual  changes  and  the  changes  involved 
in  accommodation  and  in  convergence.  These  facts  in  them¬ 
selves  are  suggestive  of  the  relatively  secondary  importance  of 
vision  in  the  life  of  this  animal. 

It  is  thus  seen  that  the  attempt  to  eliminate  the  function  of 
kinaesthetic  impulses  by  irregularly  changing  the  distance  has 

'The  term  kinaesthetic  as  here  employed  necessarily  includes  whatever 
impulses  come  from  the  skin  of  the  feet.  These  impulses  are  presumably 
fused  with  those  from  the  muscles. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


lOI 


not  been  successful  in  isolating  the  role  of  vision,  by  reason  of 
the  fact  that  when  the  distance  is  altered  the  habit  breaks 
down  and  readjustment  must  take  place.  Had  the  animals 
been  able  to  accommodate  to  the  changed  conditions  without 
trial  movements,  the  conclusion  that  the  visual  complex  (visual 
impulse,  accommodation  and  convergence)  was  the  essential 
sensory  factor  involved  in  this  coordination  would  be  justified. 
But  since  trial  movements  are  necessary,  the  problem  remains 
as  to  whether  kinaesthetic  impulses  alone  are  responsible  for  it. 

c.  Effect  of  Changing  Direction  of  Jump. 

The  experiments  summarized  on  p.  92  and  p.  98  were  much 
more  successful  in  giving  evidence  of  the  function  of  a  distance 
receptor.  Since  the  possibility  of  the  use  of  olfaction  as  a 
sensory  control  had  been  practically  eliminated  by  previous 
experiment  by  precautionary  methods  above  described,  and 
since  audition  could  not  have  furnished  such  guidance,  it  is 
evident  that  vision  or  some  other  undetermined  receptor,  func¬ 
tioned  here  in  such  a  way  as  successfully  to  control  the  adjust¬ 
ment  to  a  distant  stimulus.  Assuming  for  argument  that 
vision  is  the  effective  source  of  control,  it  may  be  maintained 
that  the  visual  impulse  seems  to  afford  evidence  concerning 
the  direction  of  the  stimulus  but  is  apparently  not  alone  capable 
of  controlling  the  amount  of  innervation  necessary  to  make 
the  requisite  adjustments.  In  other  words,  visual  impulses  in 
such  a  form  as  may  be  designated  white  light  vision  are  opera¬ 
tive^  and  afford  a  basis  for  controlling  the  direction  of  the 
adjustments,  but  do  not  operate  so  as  to  furnish  information 
concerning  the  third  dimension. 

Four  rats  of  the  six  were  able  to  adjust  accurately  and  imme¬ 
diately  to  any  direction  of  Platform  II,  (p.  92).  A  fifth 
was  successful  in  five  out  of  twelve  trials  including  the  first. 
The  sixth  rat,  (when  she  was  not  jumping  through  a  slit  in 
the  canvas  before  the  cabinet  was  lined  with  other  material) 
made  the  adjustment  correctly  in  five  trials  out  of  six. 

^Watson  {Animal  Education,  p.  85)  remarks  “other  things  being  equal, 
rats  show  a  decided  preference  for  well-lighted  rather  than  dark  places.” 


102 


FLORENCE  RICHARDSON. 


In  the  experiment  in  which  both  the  distance  and  direction 
were  changed,  the  two  rats  tested  made  the  successful  coordi¬ 
nation.  In  this  test,  it  will  be  recalled,  the  rat  was  obliged  to 
jump  downward  and  outward  to  reach  Platform  II,  a  hori¬ 
zontal  distance  of  i6  inches  from,  and  a  vertical  distance  of 
10  inches  below  Platform  1.  The  downward  jump  had  not 
hitherto  been  required  in  the  experiment,  and  the  animals 
accommodated  themselves  to  the  change  immediately.  Pos¬ 
sibly  this  immediate  accommodation  was  due  to  the  fact  that 
Platform  II,  being  lo  inches  below  the  level  of  Platform  I, 
afforded  a  visual  stimulus  area  about  four  times  larger  than 
when  in  the  horizontal  plane  of  Platform  I.  The  stimulus  was 
thereby  much  more  effective.  This  fact  of  instant  adjustment 
to  a  directional  change,  and  a  trial  and  error  method  of  adjust¬ 
ment  to  a  merely  distance  change,  is  the  basis  for  the  assumption 
that  vision  (or  some  other  unknown  distance  receptor)  affords 
information  as  to  the  direction  but  not  as  to  the  distance,  of  the 
stimulus.  The  observation  that  while  the  animals  could  jump 
downward  to  Platform  II  at  i6  inches  distant  horizontally 
from  the  support  of  Platform  I  and  lo  inches  below  it,  but 
not  at  8  inches  horizontal  distance  [and  lo  inches  below]  con¬ 
firms  an  earlier  statement  that  vision  is  in  many  instances 
overruled  by  the  habitual  innervation  tendency. 

The  possibility  of  a  directional  factor  seems  to  receive  some 
confirmation  in  the  results  of  the  test.  Of  the  eight  cases  of 
miscoordination  (not  due  to  jumping  toward  the  canvas) 
four  were  jumps  toward  the  east,  the  direction  in  which  the 
jump  was  learned,  and  four  were  toward  the  south,  the  direction 
of  the  first  jump  after  the  change.  What  the  nature  of  such  a 
factor  may  be  the  present  test  made  no  attempt  to  investigate. 
Whether  it  was  this  factor  which  led  to  the  breakdown  of  the 
coordination  in  the  case  of  every  rat  but  one  is  a  question  which 
only  further  experimentation  can  solve. 


PART  SECOND 


A.  EFFECT  OF  TRAINING  UPON  THE  RATS. 

I.  Experimental  Results. 

I.  Comparison  of  Records  of  Trained  and  of  Untrained  Rats. 

a.  Normal  White  Rats  on  Problem  I. 

While  training  two  female  white  rats  upon  Problem  I  for 
a  purpose  other  than  that  of  these  tests,  it  was  found  that  their 
time-records  were  lower  than  normal.  They  had  previously 
learned  the  Hampton  Court  maze.  Thinking  that  this  lower 
time  record  might  be  the  result  of  tuition,  the  records  of  these 
rats  were  preserved  in  order  that  they  might  be  compared  with 
those  of  normal  untrained  animals  upon  the  same  problem. 
In  Table  XII  is  given  the  averages  of  the  trained  and  of  the 
untrained  groups;  and  on  Plate  V  is  shown  the  averages  of 
both  groups. 

Table  XII. 


Showing  (l)  the  average  time-record  of  8  untrained  normal  white  rats,  (2)  the 
average  time-record  of  two  trained  normal  white  rats,  and  (3)  the  time-records 
of  a  trained  blind  anosmic  rat  upon  Problem  I. 


NO.  OF  TRIALS. 

I. 

2. 

3- 

mtn. 

min. 

min. 

I 

7.04 

5-69 

•55 

2 

1 .69 

•23 

.18 

3 

.48 

.09 

•30 

4 

.80 

•43 

.  12 

5 

■35 

.  10 

.07 

6 

•30 

•05 

.  1 1 

7 

•25 

.09 

.  10 

8 

•23 

.11 

.06 

9 

.27 

•05 

•30 

10 

.18 

.  10 

.  12 

II 

.  16 

•05 

.05 

12 

■  13 

•  14 

.08 

104 


FLORENCE  RICHARDSON. 


Table  XII. — Continued. 


NO.  OF  TRIALS. 

I. 

2. 

3- 

13 

•15 

•05 

•17 

14 

.09 

.05 

.05 

15 

.11 

•05 

.22 

16 

•14 

•14 

.  10 

17 

.18 

.08 

.12 

18 

•13 

.04 

.07 

19 

.19 

.06 

.22 

20 

.09 

.04 

.05 

21 

•17 

.06 

.  10 

22 

.  12 

.06 

•05 

23 

.  II 

.07 

.  10 

24 

•23 

•37 

.  1 1 

25 

•H 

.07 

•05 

26 

.  10 

.  12 

.  II 

27 

.08 

•15 

.04 

28 

.  12 

.06 

•05 

29 

•15 

.  10 

.04 

30 

.07 

.09 

.08 

31 

.07 

.06 

.06 

32 

.06 

•05 

.05 

33 

.  12 

.07 

.06 

34 

•17 

.05 

.07 

35 

.09 

•15 

.07 

36 

.19 

■05 

.  12 

37 

■14 

.04 

.07 

38 

.09 

.05 

.  10 

39 

.09 

•05 

.  10 

40 

.09 

■03 

.07 

41 

•24 

.04 

.08 

42 

•15 

.06 

.09 

43 

.  12 

•05 

.06 

44 

.  1 1 

.21 

•14 

■  45 

.  10 

04 

.05 

46 

.06 

.04 

.05 

47 

.06 

•05 

.07 

48 

.06 

.  12 

.06 

49 

.06 

•05 

.05 

50 

•23 

.04 

.07 

The  comparison  shows  that  the  averages  of  these  trained 
normal  animals  are  far  below  those  of  the  untrained  normal 
white  rats.  The  average  of  their  records  is — in  the  main — 
below  the  minimal  time-records  of  the  normal  untrained  group. 


Minut 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


105 


If)  4*  tO 


io6 


FLORENCE  RICHARDSON. 


The  average  of  the  lowest  two  records  of  the  normal  group  is 
considerably  above  that  of  the  average  of  these  two  experienced 
rats.  No  conclusions  are  justifiable  upon  the  results  of  this 
comparison,  since  the  two  animals  might  have  been  extreme 
variations.  The  records  are,  therefore,  tentatively  put  forth 
in  connection  with  those  of  other  trained  and  untrained  groups. 

The  records  of  these  two  trained  females  averaged  by  tens 
in  a  series  are  given  below.  They  may  be  compared  with  other 
records  of  the  same  kind  on  p.  21. 

The  Average  Time-Records  of  the  two  Females  for  Entire  Series. 

min.  min. 

Femalel . 19  Femalell . 20 

Average  Time-Records  by  Groups  of  Ten. 

Female  I.  Female  II. 


Trials.  min.  min. 

I-IO . 68  .71 

ir-20 . 08  .06 

21-30 . 06  .10 

31-40 . 07  .05 

41-50 . 07  .07 


Female  I  made  a  total  of  five  errors,  and  Female  II  a  total 
of  six  errors  in  the  series. 

b.  Blind  Anosmic  Rat  on  Problem  I. 

The  time-records  of  the  blind  anosmic  rat  upon  this  problem 
are  given  in  Table  XII.  He  had  been  trained  in  the  maze 
during  a  long  series  of  tests.  This  rat  was  undoubtedly  a  very 
robust  animal.  His  records  on  Problem  I  are  much  below 
those  of  the  untrained  normal  rats,  the  blind  rats,  or  the  anos¬ 
mic  rats  with  vision.  He  became  very  active  when  put  into 
the  control  cage  and  attacked  the  problem  at  once. 

The  Average  Time-Record  for  Entire  Series  (50  Trials). 


Blind  Anosmic  Rat . lo  min- 

Average  Time-Records  by  Groups  of  Ten. 

min.  min. 

.08 
.07 


i-io. . 
11-20 
21-30 


.19  31-40 
.11  41-50 
.07 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT.  107 

This  record  may  be  compared  with  those  of  the  other  rats 
which  are  given  in  the  section  on  Problem  I  (p.  21). 

Each  of  the  two  curves,  representing  the  averages  of  rats 
which  had  had  previous  training,  are  lower  than  any  one  of 
those  representing  the  averages  of  untrained  white  ratsd 

c.  Normal  White  Rats  on  Problem  HE 

Four  untrained  normal  white  rats  were  set  to  work  upon 
the  problem.  Three  of  the  animals  were  males  about  150 
days  of  age,  and  one  female  128  days  of  age.  The  method  of 
conducting  the  experiment  was  the  same  as  in  the  earlier  test. 
The  rats  were  tame  and  in  good  physical  condition. 

Their  method  of  solving  the  problem  was  the  same  as  that 
of  the  trained  animals,  except  that  the  untrained  rats  con¬ 
sumed  much  miore  time  in  achieving  their  first  successes.  The 
minimal  time  record  for  the  first  trial  was  more  than  29  min¬ 
utes.  The  rats  were  energetic  and  industrious,  but  they 
spent  a  great  deal  of  time  examining  the  control  cage,  though, 
like  the  trained  animals  they  had  been  fed  for  three  days  in 
the  cage  to  accustom  them  to  the  environment.  Their  average 
was  not  reduced  to  one  minute  until  the  fifth  trial.  The 
averages  of  the  trained  rats  on  the  other  hand  did  not  go  above 
one  minute  after  the  first  trial.  The  averages  of  the  untrained 
rats  were  reduced  to  .  10  min.  at  the  twenty-first  trial  though  they 
were  higher  thereafter;  while  the  averages  of  the  trained  animals 
dropped  below  .10  min.  on  the  seventh  trial  and  were  later 
no  higher. 

Table  XIII  and  Plate  VI  show  the  averages  of  these  trained 
and  untrained  animals. 

The  curves  show  very  plainly  the  great  difference  in  time- 
records  of  the  early  successes  and  also  show  the  fact  that 
even  from  the  thirty-fifth  to  the  fortieth  trial  the  records  of 
the  untrained  rats  were  not  so  low  nor  so  uniform  as  those  of 
the  trained  rats  from  the  tenth  to  the  fifteenth  trial. 

‘  In  view  of  a  possible  difference  in  the  function  of  vision  between  white  rats 
and  those  having  pigmented  eyes,  it  is  no  more  than  fair  to  limit  the  comparison 
here  to  records  of  albino  rats. 


Io8  FLORENCE  RICHARDSON. 

Table  XIIL 

Showing  the  average  time-records  of  trained  and  of  untrained  normal  white  rats 
on  Problem  III .  The  first  column  of  averages  represents  the  group  of  seven 
trained  rats;  the  second,  the  third,  and  the  fourth  columns,  the  average,  the 
minimum,  and  the  maximum  time-records  of  the  untrained  rats. 


NO.  OF  TRIAL. 

AVERAGE. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

7nin, 

min. 

min. 

I 

5.72 

40.14 

29-15 

54-38 

2 

•32 

5-97 

2.76 

13-17 

3 

•33 

.80 

1 .28 

11.27 

4 

•  17 

1-n 

.62 

13-87 

5 

•29 

.92 

•45 

2.17 

6 

.22 

.91 

•55 

1.65 

7 

.09 

.99 

•25 

2.58 

8 

.09 

■31 

.07 

-98 

9 

.06 

•43 

.22 

■IS 

10 

.06 

.28 

.20 

-43 

II 

.07 

.24 

.  12 

■31 

12 

.05 

•13 

.08 

-25 

13 

.05 

.22 

.07 

•35 

14 

.05 

•23 

•  14 

•30 

15 

•05 

•23 

•13 

•35 

16 

•15 

.  10 

•25 

17 

.21 

.  10 

•45 

18 

.19 

.  12 

•27 

19 

.22 

.08 

•43 

20 

.  1 1 

■05 

.18 

21 

.OQ 

•03 

.22 

22 

.08 

•03 

.18 

23 

.08 

•03 

•17 

24 

.  10 

•03 

.28 

25 

•  17 

.02 

-58 

26 

.08 

•03 

.20 

27 

.07 

.04 

.  10 

28 

.06 

•03 

.  10 

29 

.06 

•03 

•15 

30 

.04 

•03 

.05 

d.  Normal  Black-and-White  Rats  on  Problem  III. 

Table  XIV  and  Plate  VII  show  the  averages  of  the  trained 
and  untrained  groups  of  black-and-white  rats  on  this  problem. 

The  difference  in  the  two  curves  is  rather  startling  and  calls 
for  some  descriptive  comment. 


Minutea 


d  STUnr  OF  SENSORT  CONTROL  IN  THE  RAT. 


109 


« 


I  lO 


FLORENCE  RICHARDSON. 


Table  XIV. 

Showing  the  average  time-records  of  trained  and  of  untrained  normal  black-and- 
white  rats  on  Problem  III.  The  first  column  gives  the  averages  of  the  trained 
animals;  the  second,  the  third,  and  the  fourth,  give  respectively  the  averages, 
the  minimum,  and  the  maximum  time-records  of  the  untrained  animals. 


NO.  OF 

TRIAL. 

AVERAGE. 

AVERAGE. 

MINIMUM. 

MAXIMUM. 

min. 

min. 

min. 

min. 

I 

•99 

7.09 

1.62 

12.65 

2 

•49 

4-97 

3-42 

6.42 

3 

.  12 

1.23 

•72 

1.70 

4 

.29 

2.76 

•32 

4-25 

5 

•09 

9-15 

.40 

25.78 

6 

.11 

.76 

•43 

1-33 

7 

.07 

2.44 

.20 

6.63 

8 

.04 

.67 

•41 

•87 

9 

.08 

1-35 

1 .00 

1.95 

10 

.06 

■57 

.18 

1.28 

II 

•14 

.21 

.11 

.28 

12 

.04 

•23 

.18 

.28 

13 

•05 

.80 

.07 

1.42 

14 

.07 

•15 

.07 

•27 

15 

.04 

.18 

•13 

.22 

16 

.07 

.21 

•13 

•32 

17 

.04 

.  12 

.08 

•17 

18 

.04 

.  10 

•03 

•^7 

19 

.06 

.14 

.09 

.22 

20 

.08 

•  H 

.05 

.28 

21 

.09 

.08 

.07 

.08 

22 

•05 

.07 

.04 

.18 

23 

.04 

.  10 

.05 

.  10 

24 

.04 

.08 

•05 

.07 

25 

.04 

.05 

.04 

.09 

26 

.04 

.07 

•05 

.08 

27 

•03 

.09 

.07 

.  12 

28 

•05 

.  10 

•05 

•15 

29 

.08 

.07 

.  10 

30 

.06 

•05 

.07 

31 

.04 

•03 

.07 

32 

.06 

.04 

.08 

33 

.05 

.04 

.06 

34 

.04 

•03 

.08 

35 

.07 

.04 

.  II 

36 

.05 

.04 

.06 

37 

.05 

.07 

.06 

38 

.07 

.06 

.06 

39 

.05 

.04 

.05 

40 

.06 

.05 

.07 

nulfts 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


Ill 


is 

*5 


I  12 


FLORENCE  RICHARDSON. 


The  untrained  animals  were  tame  but  naturally  not  so  tame 
as  the  trained  rats  when  they  began  on  this  problem.'  Two 
of  them  were  frightened  by  the  opening  of  the  door;  one  rat 
was  particularly  careful  not  to  approach  the  door  from  the 
front,  but  came  up  to  it  cautiously  from  the  left  so  as  not  to 
be  too  near  when  the  door  should  fly  back.  The  rats  did  not 
locate  the  position  of  the  door  at  once  as  the  trained  animals 
had  done.  This  is  doubtless  one  cause  of  the  very  high  aver¬ 
ages  up  to  the  tenth  trial,  the  other  apparent  cause  being  the 
avoidance  of  the  door. 

e.  Blind  Rats  on  Problem  III. 

The  experimenter  desired  to  complete  the  comparisons  with 
a  discussion  of  dilperences  as  shown  in  the  records  of  the  be¬ 
havior  of  experienced  and  inexperienced  blind  rats  on  Problem 
III.  When  the  records  were  assembled  it  was  found  that  the 
individual  and  accidental  variations  were  so  high  among  the 
defective  animals  that  the  averages  of  so  small  a  group  would 
be  valueless  in  a  comparison.  Table  XV  shows  the  time  records 
for  each  individual. 

At  the  time  of  the  experiment,  but  three  inexperienced  blind 
rats  were  available.  Of  these  one  made  exceedingly  poor 
time  records  for  the  first  ten  trials  of  the  series,  and  his  generally 
poor  records  throughout  were  a  marked  variation.  Another 
animal  made  uniformly  poor  records  as  compared  with  the 
experienced  blind  rats,  while  the  third  rat  was  by  far  the  most 
active  of  the  twelve  blind  rats  that  were  experimented  upon. 
His  records  represent  a  marked  variation  in  the  other  extreme. 
Consequently,  an  average  of  the  records  of  these  three  animals 
would  be  valueless  as  a  basis  for  comparison  with  any  other 
group. 


*  The  untrained  animals  were  all  of  one  litter,  were  no  days  old,  and  were 
of  the  same  parentage  as  the  litter  of  trained  rats.  The  mother  of  the  rats  was 
the  most  active  and  energetic  animal  that  had  been  tested  in  any  of  the  experi¬ 
ments. 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT. 


1 13 


Table  XV. 


Showing  the  individual  time-records  of  three  untrained  blind  rats  on  Problem  Ill. 


NO.  OF  TRIAL. 

MALE  I. 

FEMALE  I. 

FEMALE  II. 

I 

4-77 

6.32 

6.47 

2 

1-45 

15.72 

I  .  30 

3 

.28 

•35 

•65 

4 

.28 

1.87 

.28 

5 

.18 

4.17 

3-5° 

6 

•30 

5-13 

1.03 

7 

.  12 

6-37 

•53 

8 

•15 

5-53 

•97 

9 

10.15 

12.73 

.80 

10 

.18 

18.55 

.65 

1 1 

.  12 

15.98 

.90 

12 

•13 

12.42 

•42 

13 

.  12 

1 .08 

1-45 

14 

•13 

•45 

1-33 

15 

.12 

.20 

3-5° 

16 

.08 

10.98 

1 . 10 

17 

1.87 

1.95 

18 

•27 

1. 17 

19 

1.25 

2.28 

20 

1-57 

1 .92 

21 

•25 

2.58 

22 

.28 

.88 

23 

1 .60 

•78 

24 

1 .02 

•05 

25 

•27 

1.32 

26 

1.56 

1.95 

27 

•17 

1.87 

28 

.20 

1.28 

29 

•37 

•75 

30 

1.38 

.68 

31 

•57 

I .  II 

32 

.27 

•53 

33 

•93 

•43 

34 

•32 

.60 

35 

•17 

•75 

36 

.22 

37 

•37 

38 

* 

.08 

39 

•45 

40 

.28 

FLORENCE  RICHARDSON. 


II4 


2.  Summary  of  F acts  Brought  Out  172  Foregoing  Experiments. 

The  comparison  of  the  time-records  and  of  the  learning 
curves  of  each  group  of  untrained  rats  with  a  group  corre¬ 
sponding  in  age,  variety  (albino,  or  black-and-white),  and 
condition  (normal  or  defective)  show  that  in  every  instance — 
with  the  possible  exception  of  the  case  of  the  blind  rats  which 
cannot  be  cited  as  either  confirmatory  or  contradictory — the 
trained  animals  made  uniformly  better  records  than  the  corre¬ 
sponding  groups  of  untrained  ratsd 

II.  CONCLUSIONS. 

In  view  of  the  differences  exhibited  between  the  curves  of 
the  several  groups  of  trained  and  untrained  animals,  it  seems 
advisable  to  analyze  the  experience  acquired  in  the  solution  of 
the  previous  problems.  The  first  consideration  is  the  effort 
to  formulate  a  statement  of:  (i)  What  experience  the  animal 
acquires  in  the  previous  series  of  tests,  and  (2)  what  effects 
may  be  carried  ever  from  one  situation  to  another.  Such  a 
carrying  over  might  result  either  in  a  transfer  or  an  interfer¬ 
ence  of  training.  The  curves  apparently  justify  the  statement 
that,  within  the  limits  of  such  problems  as  were  here  employed, 
those  rats  which  had  had  previous  experimental  experience 
were  more  apt  in  learning  a  new  problem.  Trained  animals 
not  only  acquire  the  requisite  association  in  a  less  number  of 
trials  but  the  early  time-records  are  shorter.  Expressed  in  terms 
of  the  neurological  and  physiological  organism,  the  shorter  time- 
record  might  be  the  result  of  a  modification  of  either  the  motor 
or  sensory  system,  or  both.  If  the  modification  were  one 
affecting  the  motor  centers  of  the  cortex  and  the  efferent  path¬ 
ways,  the  stimulus  might  (i),  release  a  greater  amount  of 
innervation,  resulting  in  greater  general  activity,  or  (2),  release 
movements  which  had  become  habitual  in  the  earlier  experience, 
and  which  would  be  advantageous  in  the  attempts  to  solve 
the  new  problem,  i.  e.,  fewer  random  movements,  and  an 
earlier  accidental  success  would  result.  If  the  modification 

^Yerkes  {The  Dancing  Mouse,  p.  263)  found  that  the  acquisition  of  one 
labyrinth  habit  facilitated  the  acquisition  of  others. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT.  115 

were  one  affecting  the  sensory  pathways  and  centers,  the 
general  result  would  be  (i)  an  increased  susceptibility  to  the 
stimulus — rendering  the  stimulus  more  intense — and  (2)  a 
decreased  resistance  in  the  connections  between  the  sensory  and 
motor  centers,  so  that  the  indirect  effect  of  the  stimulus  upon 
the  musculature  would  be  more  immediate. 

Observations  of  the  behavior  of  the  two  groups  of  animals 
lead  the  writer  to  accept  both  of  these  possibilities  as  facts; 
that  the  stimulus  is  more  intense  and  the  activity  more  imme¬ 
diate  and  better  coordinated  in  the  case  of  the  trained  as  against 
the  untrained  animal. 

Previous  to  the  work  on  Problem  III,  each  rat  had  each 
day  for  thirty-four  days  been  lifted  from  the  door  of  its  living 
cage,  put  through  the  door  of  the  control  cage  upon  the  table 
and  allowed  to  satisfy  its  hunger  from  food  which  had  to  be 
reached  by  its  own  exertions.  It  is  reasonable  to  suppose  that 
after  such  a  long  process  of  habituation  to  such  experimiental 
situations,  the  experience  of  being  lifted  from  the  living  cage, 
carried  to  a  distance  and  placed  into  another  cage,  might 
become  for  the  rat  a  stimulus  to  activity  when  placed  in  the 
control  cage. 

In  Problem  II,  given  just  previous  to  III,  the  entrance  of 
the  problem  box  occupied  the  same  relative  position,  i.  e., 
on  the  lower  left-hand  corner  of  the  south  side  of  the  food  box. 
When  the  trained  rats  were  put  into  the  cage  containing  Box 
III,  they  went  to  this  position  and  began  to  ‘nose’  about. 
The  contact  sensations  apparently  released  motor  impulses 
which  resulted  in  the  scratching,  biting,  pulling  and  clawing 
at  the  spring,  the  latch,  or  the  edge  of  the  door.  The  first 
success  soon  followed.  When  the  untrained  rats  were  put  into 
the  cage,  the  environment  was  a  stimulus  to  only  the  most 
general  and  uncontrolled  activity.  The  rats  examined  the  con¬ 
trol  cage  as  well  as  the  box.  They  sniffed  at  the  food  and  the 
latch,  and  then  went  on  to  examine  other  parts  of  the  box  and 
the  cage.  They  often  sat  down  to  wash  their  faces  and  scratch 
themselves  spending  far  more  time  at  this  procedure  than  did 
the  trained  animals.  Motor  energy  in  these  animals,  in  the 
absence  of  any  more  specific  stimulus,  seemed  to  drain  off  into 


FLORENCE  RICHARDSON. 


1 16 

these  reflex  channels.  On  the  other  hand  all  problem  boxes 
(on  account  of  past  experience)  served  as  potent  stimuli  to 
the  trained  rats;  the  animals  had  satisfied  their  curiosity  as  to 
the  surroundings  during  previous  tests  and  did  not  lack  an 
incentive  to  effort  in  the  present  environment.  Therefore  in 
the  case  of  the  trained  animals  the  stimulus  released  movements 
which  were  more  advantageous  in  the  solution  of  the  problem 
than  it  did  with  the  untrained  animals. 

The  effect  of  the  emotional  attitude  of  the  rat  has  been 
disregarded  up  to  this  point.  The  emotional  element  is  a  most 
important  and  ever  present  factor  in  the  reaction  of  the 
animals.  The  rats,  as  stated  before,  were  tame  at  the  begin¬ 
ning  of  the  experiments.  They  were  accustomed  to  being 
handled  and  when  the  door  of  the  cage  was  being  opened,  they 
came  eagerly.  At  the  end  of  the  series  this  lack  of  timidity 
had  advanced  to  a  point  that  might  be  called  familiarity. 
Instances  of  this  were  noted  on  a  number  of  occasions  when 
rats  became  ill  or  aged  and  refused  food  in  their  cages,  they 
ate  quite  freely  from  food  in  the  hands  of  the  experimenter. 

Accompanying  the  change  in  the  emotional  attitude  of  the 
rats  toward  the  experimenter  is  the  change  in  the  emotional 
attitude  toward  the  control  cage  and  to  problem  boxes  in 
general. ‘  When  this  part  of  the  environment  which  is  com¬ 
mon  to  all  the  tests  has  lost  much  of  its  novelty,  there  is  nothing 
to  interfere  with  the  normal  discharge  of  the  impulses  which 
will  speedily  result  in  adaptive  movements.  Because  the  situa¬ 
tion  as  a  whole  is  novel  to  the  inexperienced  rat,  there  is  a  state 
of  high  emotional  tension  in  which  motor  impulses,  foreign 
to  the  problem  in  hand,  are  set  up  by  the  strange  sensory 

^  The  same  behavior  as  is  here  commented  on  as  characteristic  of  trained 
animals  was  observed  in  the  case  of  two  brood  rats  which  were  bought  from  a 
small  boy.  These  rats  had  absolutely  no  fear  and  exhibited  no  signs  of  distur¬ 
bance  when  placed  in  strange  experimental  situations.  The  reactions  of  one  of 
them  which  learned  to  jump  a  distance  of  14  in.  in  the  first  day’s  test  are  described 
on  page  76.  The  other  rat  solved  Problem  III  in  much  less  time  than  any  other 
untrained  rat.  Her  records  are  not  included  in  the  tables  or  curves  as  she  was  an 
old  rat  and  did  not  conform  to  the  age  requirement  for  these  tests. 

These  instances  are  cited  in  support  of  the  contention  that  the  emotional  tone 
is  a  great  (if  not  the  greatest)  factor  in  the  ease  with  which  the  rat  adapts  itself 
to  a  new  situation. 


A  STUDT  OF  SENSORT  CONTROL  IN  THE  RAT.  1 17 

impressions.  In  the  case  of  experienced  rats  no  such  outburst 
of  motor  energy  is  incident  upon  their  introduction  to  a  new 
problem;  consequently  they  are  in  a  better  position  to  begin  work 
immediately  upon  the  elements  in  the  situation  which  are  novel. 

B.  INDIVIDUAL  AND  SEX  DIFFERENCES  AS  SHOWN  BY  BEHAVIOr. 

I.  Sex  Differences. 

All  of  the  tables  giving  the  percentages  of  minimum  and  of 
maximum  time-records  made  by  each  animal  (such  as  are 
shown  on  p.  12)  have  been  assembled  and  the  following  table 
compiled  from  the  total  number.  The  animals  are  ranked 
I,  2,  3,  etc.,  according  to  the  percentage  of  maximum  and  of 
minimum  time-records.  For  instance,  the  rat  which  made  the 
greatest  number  of  minimal  trials  is  ranked  i ;  the  rat  with  the 
next  greatest  number  is  ranked  2.  The  rat  ranked  as  i  in 
the  portion  of  the  table  showing  the  rank  in  maximum  time 
records,  is  consequently  the  animal  making  the  greatest  num¬ 
ber  of  maximum,  or  poor  time-records.  The  table  is  shown 
on  next  page. 

The  tabulation  is  of  interest,  showing  as  it  does  the  compara¬ 
tive  ranks  of  the  animal  in  the  different  problems.  It  is 
rather  striking  that  the  greatest  number  of  minimal  records 
made  in  mixed  groups  are,  with  one  exception,  to  the  credit 
of  the  males,  while  in  such  groups  the  greatest  number  ofmaxi- 
mal  records  are  made  by  the  females. '  The  least  number  of 
minimal  records,  with  one  exception,  were  made  by  females 
and  the  least  number  of  maximal  records  were  made  by  males. 
The  records  are  not  a  sufficient  basis  for  any  general  statement 
as  to  sex  differences. 

It  is  often,  but  not  always  true,  that  an  animal  which  makes 
a  good  record  on  one  problem  makes  good  records  on  the 
other  two.  The  ranking  of  the  group  of  black-and-white  rats 
on  Problem  I  and  II  are  striking. 

‘  This  is  not  true  in  Watson’s  work  on  the  maze,  in  which  the  shortest  records 
were  made  by  the  females.  Yerkes  Mow jf,  p.  276)  also  found  that  the 

females  were  superior  to  the  males  in  the  labyrinth  test,  although  the  males  were 
superior  in  discrimination  tests. 


ii8 


FLORENCE  RICHARDSON. 


Table  showing  sex  and  comparative  rank  of  each  animal  in  number  of  minimal 
and  of  maximal  time-records  on  Problems  1,  II,  and  II. 


MINIMUM. 

MAXIMUM. 

PROBLEMS. 

I. 

ii. 

III. 

PROBLEMS. 

I. 

II. 

III. 

Normal  White  Rats. 

Normal  White  Rats. 

Male  I . 

I 

3 

I 

3 

3* 

0 

Male  II . 

3* 

I 

3* 

4 

5 

0 

Male  III..  .  . 

2 

5 

5* 

4 

3 

Male  IV...  . 

3* 

6 

2 

2 

3* 

2 

Female  I .  .  . 

7 

o 

of 

I 

ot 

of 

Female  II . . 

4 

4 

o 

6 

5 

I 

Female  III . 

6 

2 

0 

5* 

I 

3 

Female  IV.  . 

5 

7 

•  oH 

4 

2 

oH 

Normal  Black-and- White  Rats. 

Normal  Black-and- White  Rats, 

Female  I . . . . 

I 

I 

4 

2 

0^ 

Female  II. .  . 

3 

3 

ol! 

3 

4 

ol 

Female  III . . 

2 

3 

2 

2 

3 

I 

Female  IV.  . 

4 

4 

I 

I 

I 

2 

Blind  Rats.  Blind  Rats. 

I 


Male  I . 

of 

o 

ot 

ot 

ot 

ot 

Male  II . 

I 

o 

of  : 

5* 

of 

ot 

Male  III..  .  . 

3 

0 

oil 

4 

ol 

ol 

Male  IV.... 

4 

6 

I  1 

6 

3 

3 

Female  I . . . 

7 

5 

oil 

I 

I 

ol 

Female  II. .  . 

2* 

4 

oil 

3 

2 

ol 

Female  III . 

2* 

3 

oil 

5* 

5 

ol 

Female  IV.  . 

6 

I 

2 

2 

4 

2 

Female  V.  .  . 

5 

2 

3  ! 

5* 

6 

I 

*  Two  or  more  animals  attained  the  same  rank  in  these  cases, 
f  Records  not  included  in  averages  but  given  under  individual  variations. 

Would  not  learn  problems. 

^  Died  before  completing  tests. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT.  iig 

2.  Individual  Differences. 

The  following  records  of  individuals  are  those  which,  for 
the  reasons  given,  were  not  included  in  the  averages  of  the 
groups,  but  are  appended  here  for  the  purpose  of  comparison 
with  the  average  records  of  the  groupd 

PROBLEM  I. 

Blind  Male  I  made  72  per  cent  of  the  total  number  of  maxi¬ 
mal  records,  although  he  made  10  per  cent  of  the  minimal 
records.  After  the  twenty-ninth  trial,  this  rat  made  every 
maximal  record.  From  the  twelfth  to  the  twenty-fourth  trial, 
his  records  were  unusually  long,  but  after  the  twenty-fourth 
his  behavior  was  such  as  to  render  his  records  incomparable 
with  those  of  the  other  blind  rats.  He  was  slow  and  made 
errors  repeatedly.  The  animal  seemed  timid  in  getting  down 
from  the  top  of  the  box.  He  was  generally  disturbed  by  the 
experimentation,  and  would  crouch  and  quiver  when  the 
experimenter  handled  him.  He  became  more  nervous  and 
irritable  as  the  tests  proceeded. 

PROBLEM  II. 

Normal  White  Female  I  was  the  slowest  of  the  group  of 
eight  normal  white  rats  which  were  tested  upon  Problem  I. 
She  was  also  the  slowest  of  the  group  on  Problem  H,  and 
here  her  time-records  represented  a  much  wider  variation  than 
in  Problem  I.  In  the  second  problem  she  was  slow  in  her 
movements  and  did  not  associate  the  act  of  stepping  out  on 
the  plane  with  the  falling  of  the  door  of  the  food  box.  Between 
the  twentieth  and  thirtieth  trials  she  established  the  habit  of 
biting  at  the  string  which  connected  the  plane  with  the  latch 
of  the  door.  She  did  not  always  go  at  once  to  the  string  and 
often  she  made  several  efforts, — at  one  time  six — before  she 
exerted  sufficient  force  to  throw  it.  These  two  causes  of  her 
long  records,  as  may  be  seen,  made  the  results  too  variable  to 
be  included  in  the  average.  In  Problem  HI,  her  records  were 
even  more  irregular. 

Yerkes  {ibid.,  p.  264  fF.)  found  wide  and  important  individual  variations 
among  his  mice. 


120 


FLORENCE  RICHARDSON. 


Blind  Male  I,  the  records  of  which  on  Problem  I  have  already 
been  shown  separately  and  commented  upon,  would  make 
no  effort  to  solve  Problem  II,  and  as  he  seemed  to  suffer 
from  great  timidity,  the  test  was  abandoned  after  five  days. 

Blind  Male  II  was  an  active,  healthy  animal,  and  solved  the 
problem  well  in  his  first  efforts  and  seemed  to  have  established 
the  association  by  the  twentieth  trial,  when  he  became  dis¬ 
turbed  by  the  falling  plane, — evidently  its  noise — and  there¬ 
after  he  avoided  it.  When  he  stepped  upon  it  at  all,  he  did 
not  step  heavily  enough  to  open  the  door.  He  made  many 
trips  to  the  plane,  then  to  the  door;  then  to  the  plane  again,  and 
finally,  when  his  efforts  were  entirely  too  erratic  to  be  useful, 
the  test  was  discontinued. 

PROBLEM  III. 

Normal  White  Female  II  made  the  maximum  time-record 
for  the  group  at  every  trial.  She  was  slow  in  her  movements 
and  in  addition  often  opened  the  latch  while  leaning  downward 
over  the  door  from  the  top  of  the  box.  She  sometimes  opened 
the  door  from  the  floor  of  the  cage,  but  never  until  after  she 
had  spent  some  time  on  the  box.  Consequently,  her  records 
are  given  separately.  In  this  problem  as  in  the  one  previous, 
she  did  not  learn  to  solve  the  problem  in  the  manner  which 
was  customary  for  the  other  animals. 

Blind  Male  II,  which  was  not  entirely  successful  in  Problem 
11  did  not  in  this  problem  reduce  his  records  to  an  approximate 
constancy  even  after  fifty  trials.  His  early  time-records  were 
both  exceedingly  long  and  variable.  The  cause  of  the  poor 
records,  as  before,  was  slowness  of  movement,  probably  the 
effect  of  his  timidity.  The  sudden  opening  of  the  door  fright¬ 
ened  him  at  the  first  trial,  and  he  crouched  motionless  for  half 
a  minute  before  he  seemed  to  regain  courage  to  move  about 
the  cage.  He  avoided  the  locality  of  the  door  quite  consist¬ 
ently  for  many  trials,  and  when  he  finally  went  to  the  door, 
his  movements  were  so  slow  and  cautious  the  time-records 
were  incomparable  with  those  of  the  other  blind  rats.  At  the 
end  of  a  series  of  78  trials,  his  time-records  were  still  long 
and  variable. 


A  STUDY  OF  SENSORY  CONTROL  IN  THE  RAT. 


I2I 


Table  XVI. 


Shoiuing  Individual  Differences  on  the  Various  Problems. 


NO.  OF  TRIAL. 

PROBLEM  I. 

PROBLEM  II. 

PROBLEM  III. 

Blind 
Male  I. 

Normal 
White 
Female  I. 

Blind 
Male  I. 

Normal 
White 
Female  I. 

Blind 
Male  I. 

I 

6.02 

2.55 

•45 

16.05 

5-33 

2 

1.63 

•73 

.19 

74  25 

5-37 

3 

1-57 

•63 

1.58 

1-45 

16.82 

4 

1 .27 

•25 

•35 

•92 

2.58 

5 

1-83 

•13 

.02 

1 .00 

•85 

6 

1. 17 

352 

•58 

1-45 

13 -42 

7 

•37 

•75 

•43 

1 .42 

11.92 

8 

.08 

•73 

5 . 60 

•36 

10.50 

9 

.98 

9.08 

1.70 

•25 

5-03 

10 

•27 

1-55 

383 

.22 

11.65 

1 1 

1 .02 

1-53 

•48 

•30 

7.28 

12 

•78 

1-77 

5-12 

1-73 

4.88 

13 

.  1 1 

10.62 

•30 

•29 

6-53 

14 

■15 

1 .27 

6. 12 

.28 

I  13 

15 

•17 

.88 

3.62 

•33 

432 

16 

•37 

.22 

4.20 

2 . 30 

17 

.  12 

•45 

2 . 17 

5.78 

18 

.  10 

•33 

3 -15 

3-37 

19 

•33 

•17 

1.03 

1-47 

20 

•15 

13 

5-75 

2.05 

21 

•25 

•50 

2 . 10 

3-47 

22 

•15 

•17 

2.13 

•75 

23 

•43 

.04 

6.28 

.42 

24 

.18 

•05 

6-33 

•37 

25 

15 

.07 

2 . 10 

1.05 

26 

•85 

1.28 

4.67 

•.30 

27 

2.62 

•3^ 

2-55 

•53 

28 

1-45 

.67 

2.87 

•87 

29 

13 

•  42 

5-25 

1. 17 

30 

1.79 

.22 

2.82 

•70 

31 

•58 

1.58 

6.23 

•15 

32 

•50 

3-75 

•72 

•25 

33 

•59 

.65 

3.08 

.20 

34 

1 .90 

1.28 

.70 

35 

3.08 

•48 

.62 

36 

■78 

•15 

•45 

37 

.62 

•33 

.60 

38 

1.72 

,40 

.68 

39 

1.30 

1 .22 

•53 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

5° 


FLORENCE  RICHARDSON 


Table  XVI. — Continued. 


PROBLEM  I 

PROBLEM  II 

PROBLEM  III 

Blind 
Male  I. 

Normal 
White 
Female  I. 

Blind 
Male  I. 

Normal 
White 
Female  I. 

Blind 
Male  I. 

1-47 

1.05 

.42 

2.68 

.65 

•85 

•74 

•90 

1-52 

I .  i6 

.98 

•97 

I -13 

1-35 

•72 

1 .66 

■52 

.72 

•65 

•38 

I  38 

.67 

•27 

•58 

.62 

•73 

1.85 

•78 

1.30 

1. 17 

•37 

1-73 

•85 

PART  THIRD 


GENERAL  CONCLUSIONS. 

The  following  paragraphs  summarize  briefly  and  schemat¬ 
ically  the  different  conclusions  drawn  from  the  results  of  the 
experiments  above  described: 

1.  No  positive  evidence  has  been  revealed  as  to  the  comp¬ 
arative  acuity  of  vision  in  animals  with  albino  eyes  and  those 
with  pigmented  eyes. 

2.  The  tests  with  three  problem-boxes  requiring  manipu¬ 
lation  for  solution  afforded  no  conclusive  evidence  of  the  func¬ 
tion  of  the  visual  impulses  in  the  successful  activities  of  the 
rats.  The  lack  of  vision,  however,  was  disadvantageous  in 
proportion  as  the  problem  demanded  finely  coordinated  and 
narrowly  localized  movements. 

3.  In  the  test  which  necessitated  a  jumping  reaction  on  the 
part  of  the  animal,  the  visual  stimulus  apparently  afforded  a 
basis  for  the  proper  control  as  to  the  direction  in  which  the 
jump  was  to  be  taken,  but  failed  signally  to  afford  any  adequate 
basis  for  accommodating  to  changes  in  distance  only.  The 
visual  impressions  were  not  a  sufficient  control  when  the  length 
of  the  jump  was  changed  and  after  a  seeming  struggle  between 
visual  and  kinaesthetic  factors,  the  coordination  broke  down 
completely.  Blind  animals  learned  to  jump  considerable  dis¬ 
tances,  but  they  were  first  given  their  orientation. 

4.  Olfactory  stimulations  had  evidently  little  importance 
in  the  problems  here  utilized.  Such  impressions  were  quite 
as  likely  to  interfere  with,  as  to  guide  the  formation  of,  the 
requisite  habit. 

5.  Tactual  impressions,  noticeably  from  the  vibrissae. 


124 


FLORENCE  RICHARDSON 


seemed  in  these  instances,  to  furnish  a  stimulus  for  many  requi¬ 
site  movements,  but  evidently  did  not  assist  in  the  following 
of  a  pathway.  The  impressions  afforded  by  the  vibrissae  were 
utilized  in  locating  projecting  surfaces  mainly  in  the  vertical 
plane. 

I 

6.  The  kinaesthetic  and  tactual  impulses  have  been  shown 
to  be  of  value  in  the  different  problems  here  employed.  These 
impulses  were  involved  as  essential  factors  in  control  not  only 
in  the  learning  processes,  but  also  in  the  reactions  after  they 
had  become  habitual.  In  the  tests  involving  jumping,  in  which 
the  conditions  were  changed  after  the  habit  had  become  estab¬ 
lished,  the  animals  were  unable  sufficiently  to  modify  the 
amount  of  innervation  required,  and,  as  shown  above,  the  reac¬ 
tions  were  consequently  unsuccessful. 

7.  There  were  noted  wide  variations  in  the  capabilities  of 
the  animals  both  as  to  amount  of  activity  and  the  capacity  of 
forming  definite  associations.  There  were  wider  variations 
among  blind  than  among  normal  animals.  Slight  sex  differ¬ 
ences  were  remarked,  though  the  range  of  sex  variation  is  less 
wide  than  that  of  individual  variation. 

8.  The  effect  of  tuition  among  the  rats  employed  in  the 
series  of  problems  is  evident.  The  animals  which  had  had 
previous  experience  in  experimental  situations  were  more  apt 
in  attacking  and  solving  new  problems.  This  was  doubtless 
due  to  two  causes:  (i)  that  the  situations  had  much  in  common, 
so  that  a  transfer  rather  than  an  interference  of  training  resulted 
and  (2)  that  the  decrease  in  emotional  tension  due  to  the  com¬ 
parative  lack  of  novelty  in  the  experimental  routine  made  the 
problem  stimulus  more  intense,  therefore  more  potent,  and 
the  resulting  activity  less  diffuse. 


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